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Kinetics of circulating endothelial progenitor cells in patients undergoing carotid artery surgery
(2016)
Aim: Endothelial progenitor cells (EPCs) are primitive cells found in the bone marrow and peripheral blood (PB). In particular, the potential of EPCs to differentiate into mature endothelial cells remains of high interest for clinical applications such as bio-functionalized patches for autologous seeding after implantation. The objective of this study was to determine EPCs’ kinetics in patients undergoing carotid artery thromboendarterectomy (CTEA) and patch angioplasty.
Methods: Twenty CTEA patients were included (15 male, mean age 76 years). PB samples were taken at 1 day preoperatively, and at 1, 3, and 5 days postoperatively. Flow cytometric analysis was performed for CD34, CD133, KDR, and CD45. Expression of KDR, SDF-1α, and G-CSF was analyzed by means of enzyme-linked immunosorbent assay.
Results: Fluorescence-activated cell sorting analysis revealed 0.031%±0.016% (% of PB mononuclear cells) KDR+ cells and 0.052%±0.022% CD45-/CD34+/CD133+ cells, preoperatively. A 33% decrease of CD45–/CD34+/CD133+ cells was observed at day 1 after surgery. However, a relative number (compared to initial preoperative values) of CD45-/CD34+/CD133+ cells was found on day 3 (82%) and on day 5 (94%) postoperatively. More profound upregulated levels of CD45–CD34+/CD133+ cells were observed for diabetic (+47% compared to nondiabetic) and male (+38% compared to female) patients. No significant postoperative time-dependent differences were found in numbers of KDR+ cells and the concentrations of the cytokines KDR and G-CSF. However, the SDF-1α levels decreased significantly on day 1 postoperatively but returned to preoperative levels by day 3.
Conclusion: CTEA results in short-term downregulation of circulating EPCs and SDF-1α levels. Rapid return to baseline levels might indicate participation of EPCs in repair mechanisms following vascular injury.
Background: Ischemia-reperfusion injury (IRI) is a major challenge in liver transplantation. The mitochondrial pathway plays a pivotal role in hepatic IRI. Levosimendan, a calcium channel sensitizer, was shown to attenuate apoptosis after IRI in animal livers. The aim of this study was to investigate the effect of levosimendan on apoptosis in human hepatocytes.
Methods: Primary human hepatocytes were either exposed to hypoxia or cultured under normoxic conditions. After the hypoxic phase, reoxygenation was implemented and cells were treated with different concentrations of levosimendan (10ng/ml, 100ng/ml, 1000ng/ml). The overall metabolic activity of the cells was measured using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), and aspartate aminotransferase (AST) levels were determined in order to quantify hepatic injury. Fluorescence-activated cell sorting (FACS) analysis was applied to measure necrosis and apoptosis. Finally, Western blotting was performed to analyze apoptotic pathway proteins.
Results: Administration of levosimendan during reperfusion increases the metabolic activity of human hepatocytes and decreases AST levels. Moreover, apoptosis after IRI is reduced in treated vs. untreated hepatocytes, and levosimendan prevents down-regulation of the anti-apoptotic protein Bcl-2 as well as up-regulation of the pro-apoptotic protein BAX.
Conclusion: The present study suggests a protective effect of levosimendan on human hepatocytes. Our findings suggest that treatment with levosimendan during reperfusion attenuates apoptosis of human hepatocytes by influencing BAX and Bcl-2 levels.
BACKGROUND: Polyclonal anti-thymocyte globulins (ATGs) are immunosuppressive drugs widely used in induction of immunosuppression and treatment of acute rejection after solid organ transplantation. We have previously demonstrated that ATGs bind to endothelial cells in vitro, and are able to modulate ECs. The aim of this study was to investigate the binding of ATGs to endothelial cells under in vivo conditions.
MATERIAL AND METHODS: Muscle biopsies from extremities of cynomolgus monkeys were obtained after ischemia/reperfusion at 4°C. ATGs (Thymoglobulin, Sanofi-Aventis, France; 1 mg/kg) were added to the blood 30 min prior to the reperfusion. Biopsies (n=10) of patients undergoing heart transplantation and preoperatively treated with ATGs (Thymoglobulin, Sanofi-Aventis, France; 1.5 mg/kg) as induction therapy were also analyzed 6 hours and 7 days after induction. Binding of ATGs to ECs was analyzed with an anti-rabbit IgG antibody by means of immunohistochemistry.
RESULTS: Binding of ATGs to endothelial cells could be demonstrated in vivo in our animal experiments 4 hours after reperfusion, as well as in the clinical biopsies 6 hours after induction of immunosuppression in heart transplant patients, showing a preferred localization in post-capillary veins. No expression of ATGs on the endothelial surface could be observed after 7 days, suggesting that ATGs may be washed out from the endothelial surface in a time-dependent manner.
CONCLUSIONS: Our results show that ATGs are able to bind to endothelial cells in an experimental model and in clinical practice, supporting preconditioning strategies with ATGs in solid organ transplantation.
Background: Infection is a main cause of morbidity and mortality after heart surgery, with multi-resistant pathogens increasingly representing a challenge. Daptomycin provides bactericidal activity against gram-positive organisms that are resistant to standard treatment including vancomycin.
Methods: A cohort of cardiac surgical patients, treated with daptomycin for major infection at two tertiary care centers, were retrospectively studied with a particular focus on the type of infection, causative pathogens and co-infections, daptomycin dosage, adverse events and outcome in order to provide evidence for the efficiency and safety of daptomycin in a distinct high-risk patient population.
Results: Sixty-five patients (87.7 % males, 60.4 ± 13.5 years) who had undergone aortic surgery (20.0 %), ventricular assist device (VAD) implantation (21.5 %), combined procedures (21.5 %), coronary artery bypass grafting (12.3 %), isolated valve surgery (15.4 %) and heart transplantation (7.7 %) were diagnosed with catheter-related infection (26.1 %), valve endocarditis (18.8 %), sternal wound (13.0 %), VAD-associated (11.6 %), cardiac implantable electrophysiological device (CIED)-associated (4.1 %), respiratory tract (4.3 %), bloodstream (4.3 %) and other infection (4.3 %). In 13.0 %, no focus of infection was identified though symptoms of severe infection were present. The most frequent pathogens were Staphylococcus epidermidis (30.4 %), Staphylococcus aureus (23.1 %) and Enterococcus species (10.1 %). Daptomycin doses ranging from 3 mg/kg every 48 h to 10 mg/kg every 24 h were administered for 15.4 ± 11.8 days. 87.0 % of the cases were classified as success, 7.2 % as treatment failure and 5.8 as non-evaluable. Adverse events were limited to one case of mild and one case of moderate neutropenia with recovery upon termination of treatment.
Conclusion: Daptomycin proved safe and effective in major infection in high-risk cardiac surgical patients.
Left ventricular non-compaction cardiomyopathy and left ventricular assist device: a word of caution
(2016)
BACKGROUND: In patients with left ventricular non-compaction (LVNC), implantation of a left ventricular assist device (LVAD) may be performed as a bridge to transplantation. In this respect, the particular characteristics of the left ventricular myocardium may represent a challenge.
CASE PRESENTATION: We report a patient with LVNC who required urgent heart transplantation for inflow cannula obstruction nine months after receiving a LVAD. LVAD parameters, echocardiography and examination of the explanted heart suggested changes of left ventricular configuration brought about by LVAD support as the most likely cause of inflow cannula obstruction.
CONCLUSIONS: We conclude that changes experienced by non-compacted myocardium during LVAD support may give rise to inflow cannula obstruction and flow reduction. Presence of LVNC mandates tight surveillance for changes in LV configuration and LVAD flow characteristics and may justify urgent transplantation listing status.
Patients with risks of ischemic injury, e.g. during circulatory arrest in cardiac surgery, or after resuscitation are subjected to therapeutic hypothermia. For aortic surgery, the body is traditionally cooled down to 18 °C and then rewarmed to body temperature. The role of hypothermia and the subsequent rewarming process on leukocyte-endothelial interactions and expression of junctional-adhesion-molecules is not clarified yet. Thus, we investigated in an in-vitro model the influence of temperature modulation during activation and transendothelial migration of leukocytes through human endothelial cells. Additionally, we investigated the expression of JAMs in the rewarming phase. Exposure to low temperatures alone during transmigration scarcely affects leukocyte extravasation, whereas hypothermia during treatment and transendothelial migration improves leukocyte-endothelial interactions. Rewarming causes a significant up-regulation of transmigration with falling temperatures. JAM-A is significantly modulated during rewarming. Our data suggest that transendothelial migration of leukocytes is not only modulated by cell-activation itself. Activation temperatures and the rewarming process are essential. Continued hypothermia significantly inhibits transendothelial migration, whereas the rewarming process enhances transmigration strongly. The expression of JAMs, especially JAM-A, is strongly modulated during the rewarming process. Endothelial protection prior to warm reperfusion and mild hypothermic conditions reducing the difference between hypothermia and rewarming temperatures should be considered.
Device-related infections in recipients of left ventricular assist devices (LVAD) have been recognized as a major source of morbidity and mortality. They require a high level of diagnostic effort as part of the overall burden resulting from infectious complications in LVAD recipients. We present a multi-allergic patient who was treated for persistent sterile intrathoracic abscess formation and pericardial empyema following minimally invasive LVAD implantation including use of a sheet of e-polytetrafluoroethylene (ePTFE) membrane to restore pericardial integrity. Sterile abscess formation and pericardial empyema recurred after surgical removal until the ePTFE membrane was removed, suggesting that in disposed patients, ePTFE may be related to sterile abscess formation or sterile empyema.
Background: The introduction of modern troponin assays has facilitated diagnosis of acute myocardial infarction due to improved sensitivity with corresponding loss of specificity. Atrial fibrillation (AF) is associated with elevated levels of troponin. The aim of the present study was to evaluate the diagnostic performance of troponin I in patients with suspected acute coronary syndrome and chronic AF.
Methods: Contemporary sensitive troponin I was assayed in a derivation cohort of 90 patients with suspected acute coronary syndrome and chronic AF to establish diagnostic cut-offs. These thresholds were validated in an independent cohort of 314 patients with suspected myocardial infarction and AF upon presentation. Additionally, changes in troponin I concentration within 3 hours were used.
Results: In the derivation cohort, optimized thresholds with respect to a rule-out strategy with high sensitivity and a rule-in strategy with high specificity were established. In the validation cohort, application of the rule-out cut-off led to a negative predictive value of 97 %. The rule-in cut-off was associated with a positive predictive value of 88 % compared with 71 % if using the 99th percentile cut-off. In patients with troponin I levels above the specificity-optimized threshold, additional use of the 3-hour change in absolute/relative concentration resulted in a further improved positive predictive value of 96 %/100 %.
Conclusions: Troponin I concentration and the 3-hour change in its concentration provide valid diagnostic information in patients with suspected myocardial infarction and chronic AF. With regard to AF-associated elevation of troponin levels, application of diagnostic cut-offs other than the 99th percentile might be beneficial.
Use of drug-eluting balloon coronary intervention prior to living donor kidney transplantation
(2014)
Background: Kidney transplantation is the gold standard of therapy in patients with terminal renal insufficiency. Living donor transplantation is a well-established option in this field. Enlarging the donor's pool implicates the acceptance of an increased rate of comorbidities. Among them, coronary artery disease is a growing problem. An increasing number of patients, undergoing living donation, receive antiplatelet therapies due to coronary disease.
Case presentation: Here we report about the perioperative treatment with a drug-eluting balloon in a patient with major cardiac risk factors who underwent kidney transplantation.
Conclusion: At the current time no recommendation can be given for the routine use of drug-eluting balloons.
A 48 year old patient with dilated cardiomyopathy and chronic acne inversa underwent implantation of a LVAD system (Heartmate II, Thoratec, USA) March 2011. During 2011 and 2012 the patient was repeatedly readmitted for treatment of driveline infection with MRSA. Colonization was controlled with Linezolid and Rifampicin however reoccurred after discontinuation. In August 2012 the LVAD-system was exchanged due to pump dysfunction (HVAD, HeartWare Inc., USA). Postoperatively, the patient presented with ascites which secreted through the driveline exit. Consequently, the abdominal wall was surgically corrected to prevent exit of peritoneal fluid through the driveline, and the patient was discharged with sterile wound swabs. However 6 weeks after discharge the driveline exit wound started secreting pus showing abundant growth of multi resistant staphylococcus aureus (MRSA). With clinical signs of increasing liver failure with regular need for paracentesis, and clinical signs of local infection, a CT scan of the abdomen was performed revealing an enrichment of contrast medium along the driveline and an abscess-like formation on the abdominal wall. Patient was admitted receiving regular dose Daptomycin and Rifampicin. The latter was discontinued after ten days. The abscess, surrounding driveline exit and abdominal wall cavity was excised and vacuum treatment initiated. Total duration of Daptomycin therapy was 3 weeks. While first week skin and wound swabs were still positive for MRSA, all samples were sterile after the second week. Inflammation was monitored by leucocyte count and IL6. The secretion of pus along the driveline ceased, the wound cavity was closed subsequently. After discharge and stop of antibiotics skin and driveline swabs remained negative for MRSA (10 weeks).