Heparin dosing in patients with Impella-supported cardiogenic shock

BACKGROUND

Impella™ is increasingly used in cardiogenic shock. However, thromboembolic and bleeding events are frequent during percutaneous mechanical circulatory support (pMCS).

OBJECTIVE

Therefore, we aimed to explore the optimal anticoagulation regime for pMCS to prevent thromboembolism and bleedings.

METHODS

This hypothesis-generating multi-center cohort study investigated 170 patients with left-Impella™ support. We (A) compared bleeding/thrombotic events in two centers with therapeutic range (TR-aPTT) activated partial thromboplastin time (60-80s) and (B) compared events of these centers with one center with intermediate range aPTT (40-60s).

RESULTS

After matching, there were no differences in patients' characteristics. In centers aiming at TR-aPTT, major bleeding was numerically lower with aPTT <60s within 48 h of left-Impella™ support, versus patients that achieved the aimed aPTT of ≥60s [aPTT ≥60s: 22 (37.3%) vs. aPTT<60s 14 (23.7%); Hazard ratio [HR], 0.62 (95%) CI, 0.28-1.38; p = 0.234]. Major cardiovascular and cerebrovascular adverse events (MACCE) did not differ between groups. In comparison of centers, TR-aPTT strategy showed higher major bleeding rates [TR: 8 (47.1%) vs. intermediate range: 1 (5.9%); HR, 0.06 (95%) CI, 0.01-0.45; p = 0.006]. MACCE were lower in the intermediate range aPTT group as well [TR 12 (70.6%) vs. intermediate range 5 (29.4%) HR, 0.32 (95%) CI, 0.11-0.92; p = 0.034].

CONCLUSION

This pilot analysis showed that lowering UFH-targets in left-Impella™ supported CS patients seems to be a safe and promising strategy for reducing major bleedings without increasing MACCE. This needs to be validated in larger, randomized clinical trials.

Possible effect of the early administration of tranexamic acid on myocardial injury in patients with severe trauma

Hemodynamic stabilization plays a crucial role in the treatment of patients suffering from severe trauma. Current guidelines recommend the early administration of tranexamic acid (TXA) for bleeding control. While less blood loss can result in less end-organ damage, including myocardial injury, TXA also exhibits prothrombotic effects with potentially adverse myocardial effects. The aim of this study was to investigate the association between the administration of TXA and myocardial injury in patients with severe trauma. We conducted a monocentric cohort study including severely injured patients ≥ 18 years [defined by Injury severity score (ISS) ≥ 16], who were admitted to a tertiary care hospital between 2016 and 2019. Primary outcome measure was myocardial injury according to the fourth Universal Definition (= high sensitive troponin T ≥ 14 ng/l). Secondary endpoints were in-hospital major adverse cardiovascular events (MACE) and mortality. Main exposure was defined as administration of TXA during prehospital period. We conducted multivariate logistic regression models including predefined covariables. A total of 368 patients were screened. Among the 297 included patients (72% male, age. 55?21 years), 119 (40%) presented myocardial injury at hospital arrival. TXA was administered to 20/297 (7%) patients in the prehospital setting, and in 96/297 (32%) patients during pre-or in-hospital period. MACE incidence was 9% (26/297) and in-hospital mortality was 26% (76/297). The adjusted odds ratios (OR) for prehospital TXA and myocardial injury, MACE and mortality were 0.75 [95% confidence interval (CI): 0.25-2.23], 0.51 [95%CI: 0.06-4.30] and 0.84 [0.21-3.33], respectively. In the present cohort of patients suffering from severe trauma, prehospital TXA did not affect the incidence of myocardial injury.

Association between early postoperative hypoalbuminaemia and outcome after orthotopic heart transplantation

OBJECTIVES

In patients undergoing heart transplantation (HTX), preoperative liver impairment and consecutive hypoalbuminaemia are associated with increased mortality. The role of early postoperative hypoalbuminaemia after HTX is unclear. This study investigated the association between early postoperative hypoalbuminaemia and 1-year mortality as well as 'days alive and out of hospital' (DAOH) after HTX.

METHODS

This retrospective cohort study included patients who underwent HTX at the University Hospital Duesseldorf, Germany, between 2010 and 2022. The main exposure was serum albumin concentration at intensive care unit (ICU) arrival. The primary endpoints were mortality and DAOH within 1 year after surgery. Receiver operating characteristic (ROC) curve analysis was performed and logistic and quantile regression models with adjustment for 13 a priori defined clinical risk factors were conducted.

RESULTS

Out of 241 patients screened, 229 were included in the analysis (mean age 55 ± 11 years, 73% male). ROC analysis showed moderate discrimination for 1-year mortality by postoperative serum albumin after HTX [AUC = 0.74; 95% confidence interval (CI): 0.66-0.83]. The cutoff for serum albumin at ICU arrival was 3.0 g/dl. According to multivariate logistic and quantile regression, there were independent associations between hypoalbuminaemia and mortality/DAOH [odds ratio of 4.76 (95% CI: 1.94-11.67) and regression coefficient of -46.97 (95% CI: -83.81 to -10.13)].

CONCLUSIONS

Postoperative hypoalbuminaemia <3.0 g/dl is associated with 1-year mortality and reduced DAOH after HTX and therefore might be used for early postoperative risk re-assessment in clinical practice.

International Survey on Perioperative Management of Patients With Infective Endocarditis

OBJECTIVES

To estimate the current practice in the perioperative management of patients undergoing cardiac surgery due to infective endocarditis.

DESIGN

A prospective, open, 24-item, web-based cross-sectional survey.

SETTING

Online survey endorsed by the European Association of Cardiothoracic Anesthesiology and Intensive Care (EACTAIC).

PARTICIPANTS

Members of the EACTAIC.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

A total of 156 responses from 44 countries were received, with a completion rate of 99%. The response rate was 16.6%. Most respondents (76%) practiced cardiac anesthesia in European hospitals, and most respondents stated that a multidisciplinary endocarditis team was not established at their center, that cardiac anesthesiologists appeared to be involved infrequently in those teams (36%), and that they were not involved in decision-making on indication and timing of surgery (88%). In contrast, the cardiac anesthesiologist performed intraoperative antibiotic therapy (62%) and intraoperative transesophageal echocardiography (90%). Furthermore, there was a relative heterogeneity concerning perioperative monitoring, as well as for coagulation and transfusion management.

CONCLUSIONS

This international survey evaluated current practice among cardiac anesthesiologists in the perioperative management of patients with infective endocarditis and the anesthesiologist's role in multidisciplinary decision-making. Heterogeneity in treatment approaches was identified, indicating relevant knowledge gaps that should encourage further clinical research to optimize treatment and postoperative outcomes in this specific population.

Pharmacological Cardioprotection against Ischemia Reperfusion Injury-The Search for a Clinical Effective Therapy

Pharmacological conditioning aims to protect the heart from myocardial ischemia-reperfusion injury (IRI). Despite extensive research in this area, today, a significant gap remains between experimental findings and clinical practice. This review provides an update on recent developments in pharmacological conditioning in the experimental setting and summarizes the clinical evidence of these cardioprotective strategies in the perioperative setting. We start describing the crucial cellular processes during ischemia and reperfusion that drive acute IRI through changes in critical compounds (∆G_ATP, Na⁺, Ca²⁺, pH, glycogen, succinate, glucose-6-phosphate, mitoHKII, acylcarnitines, BH₄, and NAD⁺). These compounds all precipitate common end-effector mechanisms of IRI, such as reactive oxygen species (ROS) generation, Ca²⁺ overload, and mitochondrial permeability transition pore opening (mPTP). We further discuss novel promising interventions targeting these processes, with emphasis on cardiomyocytes and the endothelium. The limited translatability from basic research to clinical practice is likely due to the lack of comorbidities, comedications, and peri-operative treatments in preclinical animal models, employing only monotherapy/monointervention, and the use of no-flow (always in preclinical models) versus low-flow ischemia (often in humans). Future research should focus on improved matching between preclinical models and clinical reality, and on aligning multitarget therapy with optimized dosing and timing towards the human condition.

Postoperative high-sensitivity troponin T predicts 1-year mortality and days alive and out of hospital after orthotopic heart transplantation

BACKGROUND

Orthotopic heart transplantation (HTX) is the gold standard to treat end-stage heart failure. Numerous risk stratification tools have been developed in the past years. However, their clinical utility is limited by their poor discriminative ability. High sensitivity troponin T (hsTnT) is the most specific biomarker to detect myocardial cell injury. However, its prognostic relevance after HTX is not fully elucidated. Thus, this study evaluated the predictive value of postoperative hsTnT for 1-year survival and days alive and out of hospital (DAOH) after HTX.

METHODS

This retrospective cohort study included patients who underwent HTX at the University Hospital Duesseldorf, Germany between 2011 and 2021. The main exposure was hsTnT concentration at 48 h after HTX. The primary endpoints were mortality and DAOH within 1 year after surgery. Receiver operating characteristic (ROC) curve analysis, logistic regression model and linear regression with adjustment for risk index for mortality prediction after cardiac transplantation (IMPACT) were performed.

RESULTS

Out of 231 patients screened, 212 were included into analysis (mean age 55 ± 11 years, 73% male). One-year mortality was 19.7% (40 patients) and median DAOH was 298 days (229-322). ROC analysis revealed strongest discrimination for mortality by hsTnT at 48 h after HTX [AUC = 0.79 95% CI 0.71-0.87]. According to Youden Index, the cutoff for hsTnT at 48 h and mortality was 1640 ng/l. After adjustment for IMPACT score multivariate logistic and linear regression showed independent associations between hsTnT and mortality/DAOH with odds ratio of 8.10 [95%CI 2.99-21.89] and unstandardized regression coefficient of -1.54 [95%CI -2.02 to -1.06], respectively.

CONCLUSION

Postoperative hsTnT might be suitable as an early prognostic marker after HTX and is independently associated with 1-year mortality and poor DAOH.

Association between hypotension and myocardial injury in patients with severe trauma

PURPOSE

During resuscitation of patients with severe trauma, guidelines recommend permissive hypotension prior to surgical bleeding control. However, hypotension may be associated with reduced organ perfusion and multiple organ dysfunction, e.g. myocardial injury. The association between hypotension and myocardial injury in trauma patients is underexplored. We hypothesized that hypotension is associated with myocardial injury in this population.

MATERIALS AND METHODS

This retrospective study included patients ≥ 18 years suffering from severe trauma [defined as Injury Severity Score (ISS) ≥ 16] that were treated in the emergency department resuscitation room between 2016 and 2019. Primary endpoint was the incidence of myocardial injury defined as high-sensitive troponin T > 14 ng/l. Main exposure was the duration of arterial hypotension during resuscitation period defined as mean arterial pressure < 65 mmHg.

RESULTS

Out of 368 patients screened, 343 were analyzed (73% male, age: 55 ± 21, ISS: 28 ± 12). Myocardial injury was detected in 143 (42%) patients. Overall in-hospital mortality was 26%. Multivariate binary logistic regression with forced entry of nine predefined covariables revealed an odds ratio of 1.29 [95% confidence interval 1.16-1.44]; p = 0.012) for the association between the duration of hypotension and myocardial injury.

CONCLUSION

The duration of hypotension during resuscitation period is independently associated with the incidence of myocardial injury in patients with severe trauma.

Myocardial Injury Is Associated with the Incidence of Major Adverse Cardiac Events in Patients with Severe Trauma

BACKGROUND

Severe trauma potentially results in end-organ damage such as myocardial injury. Data suggest that myocardial injury is associated with increased mortality in this cohort, but the association with the incidence of in-hospital major adverse cardiac events (MACE) remains undetermined.

METHODS

Retrospective cohort study including adult patients with severe trauma treated at the University Hospital Duesseldorf between January 2016 and December 2019. The main exposure was myocardial injury at presentation. Endpoints were in-hospital incidence of MACE and incidence of acute kidney injury (AKI) within 72 h. Discrimination of hsTnT for MACE and AKI was examined by the receiver operating characteristic curve (ROC) and the area under the curve (AUC). We conducted multivariate logistic regression analysis.

RESULTS

We included 353 patients in our final analysis (72.5% male (256/353), age: 55 ± 21 years). The AUC for hsTnT and MACE was 0.68 [95% confidence interval (CI): 0.59-0.78]. The AUC for hsTnT and AKI was 0.64 [95% (CI): 0.55-0.72]. The adjusted odds ratio (OR) for myocardial injury and MACE was 2.97 [95% (CI): 1.31-6.72], and it was 2.14 [95% (CI): 1.03-4.46] for myocardial injury and AKI.

CONCLUSION

Myocardial injury at presentation in patients with severe trauma is independently associated with the incidence of in-hospital MACE and AKI.

High On-Treatment Platelet Reactivity: Aspirin versus Clopidogrel

BACKGROUND

Antithrombotic regimen in patients on oral anticoagulation (OAC) post-percutaneous coronary intervention (PCI) is challenging. At least, one antiplatelet agent in combination with OAC is recommended after PCI for 6-12 months. Clopidogrel is used most frequently in this setting. However, data comparing P2Y12 inhibition with clopidogrel versus cyclooxygenase inhibition by acetylsalicylic acid (ASA, aspirin) is missing. It is well known that the antiplatelet effects of ASA and clopidogrel are frequently impaired (high on-treatment platelet reactivity [HTPR]). In this pilot investigation, we compared the antiplatelet effects of clopidogrel versus ASA.

METHODS

In this retrospective single-center database analysis, we investigated platelet reactivity by light transmission aggregometry in patients under different antiplatelet regimes. Results were presented as maximum of aggregation (MoA). HTPR to ASA and to clopidogrel were assessed.

RESULTS

755 patients were enrolled. 677 were on ASA, 521 were on clopidogrel, and 198 had OAC. Overall mean age was 73 ± 13.4 years, and 458 (60.7%) were male. HTPR to ASA occurred in 94/677 patients (13.9%), and mean arachidonic acid-induced MoA was 14.15 ± 19.04%. HTPR to clopidogrel occurred in 241/521 patients (46.3%), and mean adenosine diphosphate-induced MoA was 50.06 ± 20.42%. HTPR to clopidogrel was significantly more frequent than HTPR to ASA; single antiplatelet therapy (SAPT)-mono ASA: 27/199 (13.6%) versus mono clopidogrel: 6/18 (33.3%); p = 0.037; SAPT with OAC-OAC with ASA: 8/35 (22.9%) versus OAC with clopidogrel: 27/60 (45%); p = 0.046. Same difference in HTPR contingency could be shown in subgroups of dual antiplatelet therapy and ASA + clopidogrel + OAC therapy.

CONCLUSION

Impaired pharmacodynamic response to clopidogrel was more frequent as HTPR to ASA. Hence, ASA should be tested in combination with OAC post-PCI.

Validation of days alive and out of hospital as a new patient-centered outcome to quantify life impact after heart transplantation

The number of patients waiting for heart transplantation (HTX) is increasing. Thus, identification of outcome-relevant factors is crucial. This study aimed to identify perioperative factors associated with days alive and out of hospital (DAOH)-a patient-centered outcome to quantify life impact-after HTX. This retrospective cohort study screened 187 patients who underwent HTX at university hospital Duesseldorf, Germany from September 2010 to December 2020. The primary endpoint was DAOH at 1 year. Risk factors for mortality after HTX were assessed in univariate analysis. Variables with significant association were entered into multivariable quantile regression. In total, 175 patients were included into analysis. Median DAOH at 1 year was 295 (223-322) days. In univariate analysis the following variables were associated with reduced DAOH: recipient or donor diabetes pre-HTX, renal replacement therapy (RRT), VA-ECMO therapy, recipient body mass index, recipient estimated glomerular filtration rate (eGFR) and postoperative duration of mechanical ventilation. After adjustment, mechanical ventilation, RRT, eGFR and recipient diabetes showed significant independent association with DAOH. This study identified risk factors associated with reduced DAOH at 1-year after HTX. These findings might complement existing data for outcome of patients undergoing HTX.

Noninvasive evaluation of the hemodynamic status in patients after heart transplantation or left ventricular assist device implantation

INTRODUCTION

Hemodynamic assessment is crucial after heart transplantation (HTX) or left ventricular assist device (LVAD) implantation. Gold-standard is invasive assessment via thermodilution (TD). Noninvasive pulse contour analysis (NPCA) is a new technology that is supposed to determine hemodynamics completely noninvasive. We aimed to validate this technology in HTX and LVAD patients and conducted a prospective single-center cohort study.

METHODS

Patients after HTX or LVAD implantation underwent right heart catheterization including TD. NPCA using the CNAP Monitor (V.5.2.14; CNSystems Medizintechnik AG, Graz, Austria) was performed simultaneously. Three TD measurements were compared with simultaneous NPCA measurements for hemodynamic assessment. To describe the agreement between TD and NPCA, Bland-Altman analysis was done.

RESULTS

In total, 28 patients were prospectively enrolled (HTX: n = 10, LVAD: n = 18). Bland-Altman analysis revealed a mean bias of +1.05 l/min (limits of agreement ± 4.09 l/min, percentage error 62.1%) for cardiac output (CO). In LVAD patients, no adequate NPCA signal could be obtained. In 5 patients (27.8%), any NPCA signal could be detected, but was considered as low signal quality.

CONCLUSION

In conclusion, according to our limited data in a small cohort of HTX and LVAD patients, NPCA using the CNAP Monitor seems not to be suitable for noninvasive evaluation of the hemodynamic status.

Evaluation of clinical outcomes in patients treated with heparin or direct thrombin inhibitors during extracorporeal membrane oxygenation: a systematic review and meta-analysis

BACKGROUND

The number of patients treated with extracorporeal membrane oxygenation (ECMO) devices is increasing. Anticoagulation therapy is crucial to prevent thrombosis during ECMO therapy. Predominantly, heparin has been used as primary anticoagulant but direct thrombin inhibitors (DTI) have been established as alternatives. The aim of this systematic review and meta-analysis was to evaluate clinical outcomes in patients treated with heparin compared to different DTI during ECMO.

METHODS

A systematic search was conducted. Full scientific articles were sought for inclusion if heparin anticoagulation was compared to DTI (argatroban/bivalirudin) in ECMO patients. Risk of bias was assessed by Newcastle Ottawa scale. Primary endpoint was in-hospital mortality. Bleeding events, thrombotic events, hours of ECMO support, days of hospital stay, percentage of time within therapeutic range and time to therapeutic range were extracted from full texts as secondary endpoints. Results were presented as Forrest-plots. GRADE was used for confidence assessment in outcomes.

RESULTS

Systematic search identified 4.385 records, thereof 18 retrospective studies for a total of 1942 patients, complied with the predefined eligibility criteria:15 studies investigated bivalirudin and 3 studies investigated argatroban versus heparin. Risk of bias was high for most studies. In-hospital mortality, major bleeding events and pump-related thrombosis were less frequent in DTI group as compared to heparin [mortality-OR 0.69, 95% CI 0.54-0.86; major bleeding-OR 0.48, 95% CI 0.29-0.81; pump thrombosis-OR 0.55, 95% CI 0.40-0.76]. Additionally, percentage of time within therapeutic range was higher for DTI [SMD 0.54, 95% CI 0.14-0.94]. GRADE approach revealed a very low level of certainty for each outcome.

CONCLUSION

In this meta-analysis, DTI and especially bivalirudin showed beneficial effects on clinical outcomes in ECMO patients as compared to heparin. However, due to the lack of randomized trials, certainty of evidence is low.

TRIAL REGISTRATION

This systematic review and meta-analysis was prospectively registered at PROSPERO data base (reference number CRD42021237252 ).

Impact of Cardiopulmonary Resuscitation of Donors on Days Alive and Out of Hospital after Orthotopic Heart Transplantation

Background: The number of patients waiting for heart transplantation (HTX) is increasing. Optimizing the use of all available donor hearts is crucial. While mortality seems not to be affected by donor cardiopulmonary resuscitation (CPR), the impact of donor CPR on days alive and out of hospital (DAOH) is unclear. Methods: This retrospective study included adults who underwent HTX at the University Hospital Duesseldorf, Germany from 2010–2020. Main exposure was donor-CPR. Secondary exposure was the length of CPR. The primary endpoint was DAOH at one year. Results: A total of 187 patients were screened and 171 patients remained for statistical analysis. One-year mortality was 18.7%. The median DAOH at one year was 295 days (interquartile range 206–322 days). Forty-two patients (24.6%) received donor-CPR hearts. The median length of CPR was 15 (9–21) minutes. There was no significant difference in DAOH between patients with donor-CPR hearts versus patients with no-CPR hearts (CPR: 291 days (211–318 days) vs. no-CPR: 295 days (215–324 days); p = 0.619). Multivariate linear regression revealed that there was no association between length of CPR and DAOH (unstandardized coefficients B: −0.06, standard error: 0.81, 95% CI −1.65–1.53, p = 0.943). Conclusions: Donor CPR status and length of CPR are not associated with reduced DAOH at one year after HTX.

Days alive and out of hospital after left ventricular assist device implantation

Aims

Implantation of left ventricular assist devices (LVADs) as a bridge to transplant or as destination therapy is increasing. The selection of suitable patients and outcome assessment belong to the key challenges. Mortality has traditionally been a focus of research in this field, but literature on quality of life is very limited. This study aimed to identify perioperative factors influencing patients' life as measured by days alive and out of hospital (DAOH) in the first year after LVAD implantation.

Methods and results

This retrospective single‐centre cohort study screened 227 patients who underwent LVAD implantation at the University Hospital Duesseldorf, Germany, between 2010 and 2020. First, the influence of 10 prespecified variables on DAOH was investigated by univariate analysis. Second, multivariate quantile regression was conducted including all factors with significant influence on DAOH in the univariate model. Additionally, the impact of all variables on 1 year mortality was investigated using Kaplan–Meier curves to oppose DAOH and mortality. In total, 221 patients were included into analysis. As pre‐operative factors, chronic kidney disease (CKD), pre‐operative mechanical circulatory support (pMCS), and Interagency Registry for Mechanically Assisted Circulatory Support (INTERMACS) stadium < 3 were associated with lower DAOH at 1 year [CKD: 280 (155–322) vs. 230 (0–219), P = 0.0286; pMCS: 294 (155–325) vs. 243 (0–293), P = 0.0004; INTERMACS 1: 218 (0–293) vs. INTERMACS 2: 264 (6–320) vs. INTERMACS 3: 299 (228–325) vs. INTERMACS 4: 313 (247–332), P ≤ 0.0001]. Intra‐operative additional implantation of a right ventricular assist device (RVAD) was also associated with lower DAOH [RVAD: 290 (160–325) vs. 174 (0–277), P ≤ 0.0001]. As post‐operative values that were associated with lower DAOH, dialysis and tracheotomy could be identified [dialysis: 300 (252–326) vs. 186 (0–300), P ≤ 0.0001; tracheotomy: 292 (139–325) vs. 168 (0–269), P ≤ 0.0001]. Multivariate analysis revealed that all of these factors besides pMCS were independently associated with DAOH. According to Kaplan–Meier analysis, only post‐operative dialysis was significantly associated with increased mortality at 1 year (survival: no dialysis 89.4% vs. dialysis 70.1%, hazard ratio: 0.56, 95% confidence interval: 0.33–0.94; P = 0.031).

Conclusions

The results of this study indicate that there can be a clear discrepancy between hard endpoints such as mortality and more patient‐centred outcomes reflecting life impact. DAOH may relevantly contribute to a more comprehensive selection process and outcome assessment in LVAD patients.

Cardioprotective Properties of Humoral Factors Released after Remote Ischemic Preconditioning in CABG Patients with Propofol-Free Anesthesia-A Translational Approach from Bedside to Bench

The cardioprotective effect of remote ischemic preconditioning (RIPC) is well detectable in experimental studies but not in clinical trials. Propofol, a commonly used sedative, is discussed to negatively influence the release of humoral factors after RIPC. Further, results from experimental and clinical trials suggest various comorbidities interact with inducible cardioprotective properties of RIPC. In the present study, we went back from bedside to bench to investigate, in male patients undergoing CABG surgery, whether (1) humoral factors are released after RIPC during propofol-free anesthesia and/or (2) DM interacts with plasma factor release. Blood samples were taken from male patients with and without DM undergoing CABG surgery before (control) and after RIPC (RIPC). To investigate the release of cardioprotective humoral factors into the plasma, isolated perfused hearts of young rats (n = 5 per group) were used as a bioassay. The hearts were perfused with patients’ plasma without (Con) and with RIPC (RIPC) for 10 min (1% of coronary flow) before global ischemia and reperfusion. In additional groups, the plasma of patients with DM was administered (Con DM, RIPC DM). Infarct size was determined by TTC staining. Propofol-free RIPC plasma of male patients without DM showed an infarct size of 59 ± 5% compared to 61 ± 13% with Con plasma (p = 0.973). Infarct sizes from patients with DM showed similar results (RIPC DM: 55 ± 3% vs. Con DM: 56 ± 4%; p = 0.995). The release of humoral factors into the blood after RIPC in patients receiving propofol-free anesthesia undergoing CABG surgery did not show any cardioprotective properties independent of a pre-existing diabetes mellitus.

Neutrophil-lymphoycyte-ratio, platelet-lymphocyte-ratio and procalcitonin for early assessment of prognosis in patients undergoing VA-ECMO

The use of veno-arterial extracorporeal membrane oxygenation (VA-ECMO) is increasing, but mortality remains high. Early assessment of prognosis is challenging and valid markers are lacking. This study aimed to investigate Neutrophil–Lymphocyte Ratio (NLR), Platelet-Lymphocyte-Ratio (PLR) and Procalcitonin (PCT) for early assessment of prognosis in patients undergoing VA-ECMO. This retrospective single-center cohort study included 344 consecutive patients ≥ 18 years who underwent VA-ECMO due to cardiogenic shock. Main exposures were NLR, PLR and PCT measured within 24 h after VA-ECMO initiation. The primary endpoint was all-cause in-hospital mortality. In total, 92 patients were included into final analysis (71.7% male, age 57 ± 14 years). In-hospital mortality rate was 48.9%. Receiver operating characteristics (ROC) curve revealed an area under the curve (AUC) of 0.65 [95% confidence interval (CI) 0.53–0.76] for NLR. The AUCs of PLR and PCT were 0.47 [95%CI 0.35–0.59] and 0.54 [95%CI 0.42–0.66], respectively. Binary logistic regression showed an adjusted odds ratio of 3.32 [95%CI 1.13–9.76] for NLR, 1.0 [95%CI 0.998–1.002] for PLR and 1.02 [95%CI 0.99–1.05] for PCT. NLR is independently associated with in-hospital mortality in patients undergoing VA-ECMO. However, discriminative ability is weak. PLR and PCT seem not to be suitable for this purpose.

Mediation of the Cardioprotective Effects of Mannitol Discovered, with Refutation of Common Protein Kinases

The osmodiuretic agent Mannitol exerts cardioprotection against ischemia and reperfusion (I/R) injury when applied as a pre- and/or postconditioning stimulus. Previously, we demonstrated that these properties are mediated via the activation of mitochondrial ATP-sensitive potassium (mK_ATP) channels. However, considering Mannitol remains in the extracellular compartment, the question arises as to which receptor and intracellular signaling cascades are involved in myocardial protection by the osmodiuretic substance. Protein kinase B (Akt) and G (PKG), as part of the reperfusion injury salvage kinase (RISK) and/or endothelial nitric oxide (eNOS)/PKG pathway, are two well-investigated intracellular targets conferring myocardial protection upstream of mitochondrial potassium channels. Adenosine receptor subtypes have been shown to trigger different cardioprotective pathways, for example, the reperfusion injury. Further, Mannitol induces an increased activation of the adenosine 1 receptor (A1R) in renal cells conferring its nephroprotective properties. Therefore, we investigated whether (1) Akt and PKG are possible signaling targets involved in Mannitol-induced conditioning upstream of the mK_ATP channel and/or whether (2) cardioprotection by Mannitol is mediated via activation of the A1R. All experiments were performed on male Wistar rats in vitro employing the Langendorff isolated heart perfusion technique with infarct size determination as the primary endpoint. To unravel possible protein kinase activation, Mannitol was applied in combination with the Akt (MK2206) or PKG (KT5823) inhibitor. In further groups, an A1R blocker (DPCPX) was given with or without Mannitol. Preconditioning with Mannitol (Man) significantly reduced the infarct size compared to the control group. Co-administration of the A1R blocker DPXPC fully abolished myocardial protection of Mannitol. Interestingly and in contrast to the initial hypothesis, neither administration of the Akt nor the PKG blocker had any impact on the cardioprotective properties of Mannitol-induced preconditioning. These results are quite unexpected and show that the protein kinases Akt and PKG—as possible targets of known protective signaling cascades—are not involved in Mannitol-induced preconditioning. However, the cardioprotective effects of Mannitol are mediated via the A1R.

Platelet reactivity is higher in e-cigarette vaping as compared to traditional smoking

INTRODUCTION

Vaping emerges as alternative to standard tobacco smoking. However, there is evidence for critical cardiovascular, gastrointestinal and respiratory side effects. Nevertheless, long-term vaping effects on thrombocyte reactivity have not been investigated. Therefore, we investigated the influence of vaping on thrombocyte reactivity in comparison to standard smoking and non-smoking.

METHODS

Platelet function was measured by Multiplate Impedance Aggregometry as area under the curve (AUC). Smoking habits and characteristics were assessed by questionnaire. Results were analyzed using inverse probability of treatment weighting (IPTW) and conventional t-tests to test for robustness.

RESULTS

After IPTW adjustment, participants in all groups were balanced by age, gender, body height and weight. Collagen-induced aggregation was higher in vapers compared to non-smokers (non-smokers 52.55 ± 23.97 vs. vapers 66.63 ± 18.96 AUC, p = 0.002) and to smokers (vapers vs. smokers 49.50 ± 26.05 AUC, p < 0.0001). ADP-induced aggregation in vapers was higher compared to non-smokers (non-smokers 33.16 ± 16.61 vs. vapers 45.27 ± 18.67 AUC, p = 0.001) and was numerically increased compared to smokers (vapers vs. smokers 40.09 ± 19.80 AUC, p = 0.08). These findings remained robust in t-test analysis.

CONCLUSION

This study provides first evidence that vaping leads to enhanced platelet reactivity compared to standard smoking and non-smoking. This suggests health effects of vaping might be more severe than previously assumed. Whether this effect translates to clinical outcome with a higher incidence of major cardiovascular events, should be evaluated in large-scaled clinical studies.

Life impact of VA-ECMO due to primary graft dysfunction in patients after orthotopic heart transplantation

Aims

Primary graft dysfunction (PGD) is a feared complication after heart transplantation (HTX). HTX patients frequently receive veno‐arterial extracorporeal membrane oxygenation (VA‐ECMO) until graft recovery. Long‐term mortality of patients weaned from VA‐ECMO after HTX is comparable with non‐ECMO patients. However, impact on quality of life is unknown. This study investigated days alive and out of hospital (DAOH) as patient‐centred outcome in HTX patients at 1 year after surgery.

Methods and results

This retrospective single‐centre cohort study included patients who underwent HTX at the University Hospital Düsseldorf, Germany, from 2010 to 2020. Main exposure was VA‐ECMO due to PGD. VA‐ECMO and non‐VA‐ECMO patients were compared regarding the primary endpoint DAOH at 1 year after HTX. Subgroup analysis for patients weaned from VA‐ECMO was performed. In total, 144 patients were included into analysis; 1 year mortality was significantly lower in non‐ECMO patients [non‐ECMO 14.3% (14/98) vs. VA‐ECMO 34.8% (16/46), adjusted hazard ratio: 0.32, 95% confidence interval: 0.15–0.74; P = 0.002]. Mortality did not differ significantly between patients weaned from VA‐ECMO and non‐ECMO patients [non‐ECMO 14.3% (14/98) vs. VA‐ECMO (weaned) 18.9% (7/37), adjusted hazard ratio: 0.72, 95% confidence interval: 0.27–1.90; P = 0.48]. DAOH were significantly higher in non‐ECMO patients compared with VA‐ECMO patients and patients weaned from VA‐ECMO [non‐ECMO vs. VA‐ECMO: median 310 (inter‐quartile range 277–327) days vs. 243 (0–288) days; P < 0.0001; non‐ECMO vs. VA‐ECMO (weaned): 310 (277–327) days vs. 253 (208–299) days; P < 0.0001]. These results were still significant after multivariable adjustment with forced entry of predefined covariables.

Conclusions

Despite similar survival rates, VA‐ECMO due to PGD has a relevant life impact as defined by DAOH in the first year after HTX. As a more patient‐centred endpoint, DAOH may contribute to a more comprehensive assessment of outcome in HTX patients.

Impact of high on-treatment platelet reactivity after angioplasty in patients with critical limb ischemia

OBJECTIVES

Dual antiplatelet therapy (DAPT) with aspirin and clopidogrel is standard of care in patients with peripheral artery disease (PAD) after percutaneous transluminal angioplasty (PTA). However, high on treatment platelet reactivity (HTPR) to DAPT is frequent and associated with major adverse limb events (MALE) in PAD patients. Nevertheless, association of MALE and HTPR in patients with critical limb ischemia (CLI) is not known. Moreover, comorbidities might confound response to antiplatelet medication further. Hence, in this trial we analyzed pharmacodynamic responses to DAPT and clinical events in CLI patients post PTA.

METHODS

In this prospective single center pilot analysis, we included 71 CLI patients. Patients received DAPT after PTA. Antiplatelet effect were measured by light transmission aggregometry (LTA) and vasodilator-stimulated protein phosphorylation assay (VASP). MALE, major adverse cardiac and cerebrovascular events (MACCE) and BARC bleeding within 12 months follow-up were assessed.

RESULTS

Mean age of patients was 73.37 ± 7.36 years and 47 (66.2%) were male. Overall HTPR appeared in 46 patients (64.8%). MALE and MACCE showed no differences between patients with and patients without HTPR. However, bleeding was higher in patients with sufficient pharmacodynamic response to DAPT (Bleeding - HTPR: 13.4% vs. no HTPR: 36.0%; log-rank HR: 0.32; 95% CI 0.1079 to 0.9396 p = 0.0217). This finding remained robust in multivariate analysis.

CONCLUSION

HTPR to DAPT is frequent in CLI patients. However, bleeding was higher in patients with sufficient response to DAPT. Ischemic events did not differ. Hence, CLI patients might benefit from an alternative antithrombotic approach.

Risk Factors for Acute Kidney Injury Requiring Renal Replacement Therapy after Orthotopic Heart Transplantation in Patients with Preserved Renal Function

Acute kidney injury (AKI), requiring renal replacement therapy (RRT). is a serious complication after orthotopic heart transplantation (HTX). In patients with preexisting impaired renal function, postoperative AKI is unsurprising. However, even in patients with preserved renal function, AKI requiring RRT is frequent. Therefore, this study aimed to identify risk factors associated with postoperative AKI requiring RRT after HTX in this sub-cohort. This retrospective cohort study included patients ≥ 18 years of age with preserved renal function (defined as preoperative glomerular filtration rate ≥ 60 mL/min) who underwent HTX between 2010 and 2021. In total, 107 patients were included in the analysis (mean age 52 ± 12 years, 78.5% male, 45.8% AKI requiring RRT). Based on univariate logistic regression, use of extracorporeal membrane oxygenation, postoperative infection, levosimendan therapy, duration of norepinephrine (NE) therapy and maximum daily increase in tacrolimus plasma levels were chosen to be included into multivariate analysis. Duration of NE therapy and maximum daily increase in tacrolimus plasma levels remained as independent significant risk factors (NE: OR 1.01, 95%CI: 1.00–1.02, p = 0.005; increase in tacrolimus plasma level: OR 1.18, 95%CI: 1.01–1.37, p = 0.036). In conclusion, this study identified long NE therapy and maximum daily increase in tacrolimus plasma levels as risk factors for AKI requiring RRT in HTX patients with preserved renal function.

Fibrinogen-Albumin-Ratio is an independent predictor of thromboembolic complications in patients undergoing VA-ECMO

Veno-arterial extracorporeal membrane oxygenation (VA-ECMO) supports patients suffering from refractory cardiogenic shock. Thromboembolic complications (TeC) are common in VA-ECMO patients and are associated with increased morbidity and mortality. Valid markers to predict TeC in VA-ECMO patients are lacking. The present study investigated the predictive value of baseline Fibrinogen-Albumin-Ratio (FAR) for in-hospital TeC in patients undergoing VA-ECMO. This retrospective cohort study included patients who underwent VA-ECMO therapy due to cardiogenic shock at the University Hospital Duesseldorf, Germany between 2011 and 2018. Main exposure was baseline FAR measured at initiation of VA-ECMO therapy. The primary endpoint was the in-hospital incidence of TeC. In total, 344 patients were included into analysis (74.7% male, mean age 59 ± 14 years). The in-hospital incidence of TeC was 34%. Receiver operating characteristics (ROC) curve of FAR for in-hospital TeC revealed an area under the curve of 0.67 [95% confidence interval (CI) 0.61-0.74]. Youden index determined a cutoff of 130 for baseline FAR. Multivariate logistic regression revealed an adjusted odds-ratio of 3.72 [95% CI 2.26-6.14] for the association between FAR and TeC. Baseline FAR is independently associated with in-hospital TeC in patients undergoing VA-ECMO. Thus, FAR might contribute to the prediction of TeC in this cohort.

Complex challenges of estimating the age and vitality of muscle wounds: a study with matrix metalloproteinases and their inhibitors on animal and human tissue samples

The estimation of wound age and wound vitality is a recurring task in forensic routine work and has been subject of forensic research for a long time. By now, an unrestrictedly reliable marker or set of markers has not been found. In a study on myocardial infarctions, matrix metalloproteinases (MMP) 2 and 9 as well as tissue inhibitor of matrix metalloproteinases 1 (TIMP-1) were detected immunohistochemically in mechanically wounded myocardium (ECG electrodes, vessel ligations). Against this background, the potency of MMP-9, MMP-2, and TIMP-1 as markers for the estimation of wound age and wound vitality was tested in a broad approach with human tissue samples drawn during autopsies and with an animal model, the isolated perfused Langendorff heart. The study comprised samples of injured human skeletal muscle, injured human myocardium, rats’ hearts with vital wounds, and rats’ hearts with postmortem-inflicted wounds that were all stained immunohistochemically. The results showed great scattering, leading to the conclusion that MMP-2, MMP-9, and TIMP-1 are not suitable for wound age estimation. Merely the results for TIMP-1 suggested that this marker might be able to differentiate between vital and postmortem-inflicted wounds. With a view to the promising results of the preceding study, the results underline the necessity to test possible markers of wound age/wound vitality on a large and diverse sample set.

Combination of Cyclosporine A and Levosimendan Induces Cardioprotection under Acute Hyperglycemia

Prognosis of patients with myocardial infarction is detrimentally affected by comorbidities like diabetes mellitus. In the experimental setting, not only diabetes mellitus but also acute hyperglycemia is shown to hamper cardioprotective properties by multiple pharmacological agents. For Levosimendan-induced postconditioning, a strong infarct size reducing effect is demonstrated in healthy myocardium. However, acute hyperglycemia is suggested to block this protective effect. In the present study, we investigated whether (1) Levosimendan-induced postconditioning exerts a concentration-dependent effect under hyperglycemic conditions and (2) whether a combination with the mitochondrial permeability transition pore (mPTP) blocker cyclosporine A (CsA) restores the cardioprotective properties of Levosimendan under hyperglycemia. For this experimental investigation, hearts of male Wistar rats were randomized and mounted onto a Langendorff system, perfused with Krebs-Henseleit buffer with a constant pressure of 80 mmHg. All isolated hearts were subjected to 33 min of global ischemia and 60 min of reperfusion under hyperglycemic conditions. (1) Hearts were perfused with various concentrations of Levosimendan (Lev) (0.3–10 μM) for 10 min at the onset of reperfusion, in order to investigate a concentration–response relationship. In the second set of experiments (2), 0.3 μM Levosimendan was administered in combination with the mPTP blocker CsA, to elucidate the underlying mechanism of blocked cardioprotection under hyperglycemia. Infarct size was determined by tetrazolium chloride (TTC) staining. (1) Control (Con) hearts showed an infarct size of 52 ± 12%. None of the administered Levosimendan concentrations reduced the infarct size (Lev0.3: 49 ± 9%; Lev1: 57 ± 9%; Lev3: 47 ± 11%; Lev10: 50 ± 7%; all ns vs. Con). (2) Infarct size of Con and Lev0.3 hearts were 53 ± 4% and 56 ± 2%, respectively. CsA alone had no effect on infarct size (CsA: 50 ± 10%; ns vs. Con). The combination of Lev0.3 and CsA (Lev0.3 ± CsA) induced a significant infarct size reduction compared to Lev0.3 (Lev0.3+CsA: 35 ± 4%; p < 0.05 vs. Lev0.3). We demonstrated that (1) hyperglycemia blocks the infarct size reducing effects of Levosimendan-induced postconditioning and cannot be overcome by an increased concentration. (2) Furthermore, cardioprotection under hyperglycemia can be restored by combining Levosimendan and the mPTP blocker CsA.

Pharmacological Conditioning of the Heart: An Update on Experimental Developments and Clinical Implications

The aim of pharmacological conditioning is to protect the heart against myocardial ischemia-reperfusion (I/R) injury and its consequences. There is extensive literature that reports a multitude of different cardioprotective signaling molecules and mechanisms in diverse experimental protocols. Several pharmacological agents have been evaluated in terms of myocardial I/R injury. While results from experimental studies are immensely encouraging, translation into the clinical setting remains unsatisfactory. This narrative review wants to focus on two aspects: (1) give a comprehensive update on new developments of pharmacological conditioning in the experimental setting concentrating on recent literature of the last two years and (2) briefly summarize clinical evidence of these cardioprotective substances in the perioperative setting highlighting their clinical implications. By directly opposing each pharmacological agent regarding its recent experimental knowledge and most important available clinical data, a clear overview is given demonstrating the remaining gap between basic research and clinical practice. Finally, future perspectives are given on how we might overcome the limited translatability in the field of pharmacological conditioning.

Cardioprotective Properties of Mannitol-Involvement of Mitochondrial Potassium Channels

Cardiac preconditioning (PC) and postconditioning (PoC) are powerful measures against the consequences of myocardial ischemia and reperfusion (I/R) injury. Mannitol-a hyperosmolar solution-is clinically used for treatment of intracranial and intraocular pressure or promotion of diuresis in renal failure. Next to these clinical indications, different organ-protective properties-e.g., perioperative neuroprotection-are described. However, whether Mannitol also confers cardioprotection via a pre- and/or postconditioning stimulus, possibly reducing consequences of I/R injury, remains to be seen. Therefore, in the present study we investigated whether (1) Mannitol-induced pre- and/or postconditioning induces myocardial infarct size reduction and (2) activation of mitochondrial ATP-sensitive potassium (mKATP) channels is involved in cardioprotection by Mannitol. Experiments were performed on isolated hearts of male Wistar rats via a pressure controlled Langendorff system, randomized into 7 groups. Each heart underwent 33 min of global ischemia and 60 min of reperfusion. Control hearts (Con) received Krebs-Henseleit buffer as vehicle only. Pre- and postconditioning was achieved by administration of 11 mmol/L Mannitol for 10 min before ischemia (Man-PC) or immediately at the onset of reperfusion (Man-PoC), respectively. In further groups, the mKATP channel blocker 5HD, was applied with and without Mannitol, to determine the potential underlying cardioprotective mechanisms. Primary endpoint was infarct size, determined by triphenyltetrazolium chloride staining. Mannitol significantly reduced infarct size both as a pre- (Man-PC) and postconditioning (Man-PoC) stimulus compared to control hearts (Man-PC: 31 ± 4%; Man-PoC: 35 ± 6%, each p < 0.05 vs. Con: 57 ± 9%). The mKATP channel inhibitor completely abrogated the cardioprotective effect of Mannitol-induced pre- (5HD-PC-Man-PC: 59 ± 8%, p < 0.05 vs. Man-PC) and postconditioning (5HD-PoC-Man-PoC: 59 ± 10% vs. p < 0.05 Man-PoC). Infarct size was not influenced by 5HD itself (5HD-PC: 60 ± 14%; 5HD-PoC: 54 ± 14%, each ns vs. Con). This study demonstrates that Mannitol (1) induces myocardial pre- and postconditioning and (2) confers cardioprotection via activation of mKATP channels.

Remote ischemic preconditioning does not induce activation of Akt and STAT5 in the rat heart

Remote ischemic preconditioning (RIPC) is hypothesized to be a promising cardioprotective strategy to protect hearts against ischemia and reperfusion (I/R) injury; however, the current understanding of the underlying signal transduction pathways involved remains unclear. It has been previously demonstrated that protein kinase B/AKT, which is a crucial protein of the reperfusion injury salvage kinases pathway, and STAT5, which is a member of the survivor activating factor enhancement pathway, serve a pivotal role in cardioprotection. However, whether and at what time-points (TPs) RIPC leads to the activation of AKT and STAT5 in a rat model of RIPC and I/R injury remains to be determined. The present study hypothesized that RIPC may induce the phosphorylation of AKT and/or STAT5 immediately following RIPC and/or at a later TP with or without subsequent I/R. In the first set of experiments (part A), male Wistar rats were randomized into 2 groups (n=6 per group): The first group underwent RIPC via a hind limb tourniquet (4x5 min I/R episodes), while the second group received the respective sham treatment. In the second set of experiments (part B), the rats were randomized into 4 groups (n=6 per group) that either underwent RIPC or sham treatment prior to 35 min of ischemia by occlusion of the left anterior descending coronary artery followed by 120 min reperfusion or a respective sham treatment. At the end of the experiments, the heart tissue was isolated in order to analyze the phosphorylation levels of AKT and STAT5. The results revealed that RIPC did not induce the immediate or late phosphorylation of AKT or STAT5. In addition, following I/R, the activation of AKT and STAT5 was not modulated by RIPC. In conclusion, the findings of the present study suggested that RIPC-induced cardioprotection may not be mediated by the activation of AKT or STAT5 at the investigated TPs.

Dexmedetomidine Provides Cardioprotection During Early or Late Reperfusion Mediated by Different Mitochondrial K+-Channels

BACKGROUND

Cardioprotective interventions-such as pharmacological postconditioning-are a promising strategy to reduce deleterious consequences of ischemia and reperfusion injury (I/RI) in the heart, especially as timing and onset of myocardial infarction are unpredictable. Pharmacological postconditioning by treatment with dexmedetomidine (Dex), an α2-adrenoreceptor agonist, during reperfusion protects hearts from I/RI, independently of time point and duration of application during the reperfusion phase. The mitochondrial ATP-sensitive K (mKATP) and mitochondrial large-conductance calcium-sensitive potassium channel (mBKCa) play a pivotal role in mediating this cardioprotective effect. Therefore, we investigated whether Dex-induced cardioprotection during early or late reperfusion is mediated variously by these mitochondrial K-channels.

METHODS

Hearts of male Wistar rats were randomized into 8 groups and underwent a protocol of 15 minutes adaption, 33 minutes ischemia, and 60 minutes reperfusion in an in vitro Langendorff-system. A 10-minute treatment phase was started directly (first subgroup, early reperfusion) or 30 minutes (second subgroup, late reperfusion) after the onset of reperfusion. Control (Con) hearts received vehicle only. In the first subgroup, hearts were treated with 3 nM Dex, 100 µM mKATP-channel blocker 5-hydroxydecanoate (5HD) or 1 µM mBKCa-channel blocker Paxilline (Pax) alone or with respective combinations (5HD + Dex, Pax + Dex). Hearts of the second subgroup received Dex alone (Dex30') or in combination with the respective blockers (5HD + Dex30', Pax + Dex30'). Infarct size was determined with triphenyltetrazoliumchloride staining. Hemodynamic variables were recorded during the whole experiment.

RESULTS

During early reperfusion (first subgroup), the infarct size reducing effect of Dex (Con: 57% ± 9%, Dex: 31% ± 7%; P< .0001 versus Con) was completely abolished by 5HD and Pax (52% ± 6%; Pax + Dex: 53% ± 4%; each P< .0001 versus Dex), while both blockers alone had no effect on infarct size (5HD: 54% ± 8%, Pax: 53% ± 11%). During late reperfusion (second subgroup) the protective effect of Dex (Dex30': 33% ± 10%, P< .0001 versus Con) was fully abrogated by Pax (Pax + Dex30': 58% ± 7%, P < .0001 versus Dex30'), whereas 5HD did not block cardioprotection (5HD + Dex30': 36% ± 7%). Between groups and within each group throughout reperfusion no significant differences in hemodynamic variables were detected.

CONCLUSIONS

Cardioprotection by treatment with Dex during early reperfusion seems to be mediated by both mitochondrial K-channels, whereas during late reperfusion only mBKCa-channels are involved.

Perioperative Cardioprotection: General Mechanisms and Pharmacological Approaches

Cardioprotection encompasses a variety of strategies protecting the heart against myocardial injury that occurs during and after inadequate blood supply to the heart during myocardial infarction. While restoring reperfusion is crucial for salvaging myocardium from further damage, paradoxically, it itself accounts for additional cell death-a phenomenon named ischemia/reperfusion injury. Therefore, therapeutic strategies are necessary to render the heart protected against myocardial infarction. Ischemic pre- and postconditioning, by short periods of sublethal cardiac ischemia and reperfusion, are still the strongest mechanisms to achieve cardioprotection. However, it is highly impractical and far too invasive for clinical use. Fortunately, it can be mimicked pharmacologically, for example, by volatile anesthetics, noble gases, opioids, propofol, dexmedetomidine, and phosphodiesterase inhibitors. These substances are all routinely used in the clinical setting and seem promising candidates for successful translation of cardioprotection from experimental protocols to clinical trials. This review presents the fundamental mechanisms of conditioning strategies and provides an overview of the most recent and relevant findings on different concepts achieving cardioprotection in the experimental setting, specifically emphasizing pharmacological approaches in the perioperative context.

Effluent from ischemic preconditioned hearts confers cardioprotection independent of the number of preconditioning cycles

Coronary effluent collected from ischemic preconditioning (IPC) treated hearts induces myocardial protection in non-ischemic-preconditioned hearts. So far, little is known about the number of IPC cycles required for the release of cardioprotective factors into the coronary effluent to successfully induce cardioprotection. This study investigated the cardioprotective potency of effluent obtained after various IPC cycles in the rat heart. Experiments were performed on isolated hearts of male Wistar rats, mounted onto a Langendorff system and perfused with Krebs-Henseleit buffer. In a first part, effluent was taken before (Con) and after each IPC cycle (Eff 1, Eff 2, Eff 3). IPC was induced by 3 cycles of 5 min of global myocardial ischemia followed by 5 minutes of reperfusion. In a second part, hearts of male Wistar rats were randomized to four groups (each group n = 4–5) and underwent 33 min of global ischemia followed by 60 min of reperfusion. The previously obtained coronary effluent was administered for 10 minutes before ischemia as a preconditioning stimulus. Infarct size was determined at the end of reperfusion by triphenyltetrazoliumchloride (TTC) staining. Infarct size with control effluent was 54±12%. Effluent obtained after IPC confers a strong infarct size reduction independent of the number of IPC cycles (Eff 1: 27±5%; Eff 2: 35±7%; Eff 3: 35±8%, each P<0.05 vs. Con). Effluent extracted after one cycle IPC is comparably protective as after two or three cycles IPC.

Intraneural Application of microRNA-1 Mimetic Nucleotides Does Not Resolve Neuropathic Pain After Chronic Constriction Injury in Rats

Background

Alterations of the expression of microRNAs (miRNAs) in chronic pain models seem to play a crucial role in the development of neuropathic pain, with microRNA-1 (miR-1) being of particular interest. Recently, we were able to show that decreased miR-1 levels were associated with increased expression of brain-derived neurotrophic factor (BDNF) and Connexin 43 (Cx43). We hypothesized that miR-1 mimetic nucleotides could alleviate neuropathic pain caused by chronic constriction injury in rats.

Methods

MiR-1 mimetic nucleotides were evaluated for effectiveness, functionality, and intracellular stability by transfecting human glioblastoma cells (U-87 MG). In vivo transfection with miR-1 mimics and corresponding scrambled miRNAs serving as control was performed by repetitive injection (days 0, 3, and 7) into the sciatic nerve following chronic constriction injury (CCI) in rats. Quantitative PCR was used to measure miR-1 content. Cx43 expression was determined by Western blot analysis. Effects on neuropathic pain were assessed by detecting paw withdrawal thresholds using an automated filament application.

Results

Transfection of miR-1 mimics was confirmed in U-87 MG cells, with miR-1 content being increased significantly after 48 h and after 96 h (p<0.05). Effective downregulation of Cx43 expression was observed 48 and 96 h after transfection (−44 ± 0.07% and −40 ± 0.11%; p<0.05). In vivo, repetitive transfection with miR-1 mimetic nucleotides led to a 17.9-fold (± 14.2) increase of miR-1 in the sciatic nerve. However, the protein expression of Cx43 in sciatic nerves as well as paw withdrawal thresholds for mechanical stimulation was not significantly increased 10 days after chronic constriction injury.

Conclusion

While transfection with miR-1 mimics effective reduces Cx43 expression in vitro and restores miR-1 after CCI, we did neither observe altered levels of Cx43 protein level in nerves nor a beneficial effect on mechanical allodynia in vivo, most likely caused by insufficient Cx43 suppression.

MiR-21-5p but not miR-1-3p expression is modulated by preconditioning in a rat model of myocardial infarction

Isoflurane (Iso) preconditioning (PC) is known to be cardioprotective against ischemia/reperfusion (I/R) injury. It was previously shown that microRNA-21-5p (miR-21-5p) is regulated by Iso-PC. It is unclear, if expression of cardiac enriched miR-1-3p is also affected by Iso-PC, and associated with activation of HIF1α (hypoxia-inducible factor 1-alpha).  Male Wistar rats (n = 6–8) were randomly assigned to treatment with or without 1 MAC Iso for 30 min, followed by 25 min of regional myocardial ischemia, with 120 min reperfusion. At the end of reperfusion, myocardial expression of miR-1-3p, miR-21-5p and mRNAs of two HIF-1α-dependent genes, VEGF (vascular endothelial growth factor) and HO-1 (heme oxygenase-1), were determined by quantitative PCR. Protein expression of a miR-21 target gene, PDCD4 (programmed cell death protein 4), was assessed by western blot analysis. Infarct sizes were analyzed with triphenyltetrazoliumchloride staining. MiR-21-5p expression was increased by Iso, whereas expression of miR-1-3p was not altered. The expression of VEGF but not HO-1 was induced by Iso. Iso-PC reduced infarct sizes compared to untreated controls. No regulation of miRNA and mRNA expression was detected after I/R. PDCD4 protein expression was not affected after Iso exposure. Expression of miR-21-5p, in contrast to miR-1-3p, is altered during this early time point of Iso-PC. HIF1α signaling seems to be involved in miR-21-5p regulation.

[Management of patients with MELAS syndrome : A case report and general characteristics from an anesthesiological perspective]

BACKGROUND

Mitochondrial encephalomyopathy, lactic acidosis and stroke-like episodes (MELAS) syndrome is a rare progressive disease with acute neurological episodes caused by a mitochondriopathy. Due to a defect of oxidative phosphorylation in the respiratory chain, there is impaired mitochondrial energy production with subsequent lactic acidosis, especially in situations with increased stress. Due to the high risk of metabolic derailment MELAS syndrome is a great challenge with respect to the perioperative management of anesthesia.

OBJECTIVE

This article gives a general overview of the special features of anesthesia management in patients with MELAS syndrome. A case report is presented in order to demonstrate how intraoperative parenteral nutrition can possibly be used to counteract the formation of lactic acidosis.

MATERIAL AND METHODS

A systematic review of the literature was performed. As only very few reports on MELAS syndrome are available, a case report was also integrated into this overview article for illustration purposes.

RESULTS AND CONCLUSION

Patients with MELAS syndrome represent a challenging cohort with respect to management of anesthesia and an intensive monitoring of the metabolic status is crucial. In cases of increasing lactate values, the administration of intraoperative parenteral nutrition seems to be a suitable approach to avoid lactic acidosis and to improve the perioperative treatment of patients with MELAS syndrome in the future.

Characteristics of Dexmedetomidine Postconditioning in the Field of Myocardial Ischemia-Reperfusion Injury

BACKGROUND

Timing and onset of myocardial ischemia are mostly unpredictable. Therefore, postconditioning could be an effective cardioprotective intervention. Because ischemic postconditioning is an invasive and not practicable treatment, pharmacological postconditioning would be a more suitable alternative cardioprotective measure. For the α2-adrenoreceptor agonist, dexmedetomidine postconditioning has been shown. However, data on a concentration-dependent effect of dexmedetomidine are lacking. Furthermore, it is unclear whether the time point and/or duration of dexmedetomidine administration in the reperfusion period is of relevance. We set out to determine whether infarct size reduction by dexmedetomidine is concentration dependent and whether time point and/or duration of dexmedetomidine application has an impact on the effect size of cardio protection.

METHODS

Hearts of male Wistar rats were randomized and placed on a Langendorff system perfused with Krebs-Henseleit buffer at a constant pressure of 80 mm Hg. All hearts were subjected to 33 minutes of global ischemia and 60 minutes of reperfusion. In part I of the study, a concentration-response effect was determined by perfusing hearts with various concentrations of dexmedetomidine (0.3-100 nM) at the onset of reperfusion. Based on these results, part II of the study was conducted with 3 nM dexmedetomidine. Application of dexmedetomidine started directly at the onset of reperfusion (Dex60) and 15 minutes (Dex15), 30 minutes (Dex30), or 45 minutes (Dex45) after the start of reperfusion and lasted always until the end of the reperfusion period. Infarct size was determined by triphenyltetrazolium chloride staining.

RESULTS

In part I, infarct size in control (Con) hearts was 62% ± 4%. Three-nanometer dexmedetomidine was the lowest most effective cardioprotective concentration and reduced infarct size to 24% ± 7% (P < .0001 versus Con). Higher concentrations did not confer stronger protection. Infarct size in control hearts from part II was 66% ± 6%. Different starting times and/or durations of application resulted in similar infarct size reduction (all P < .0001 versus Con).

CONCLUSIONS

Postconditioning by dexmedetomidine is concentration dependent in ranges between 0.3 and 3 nM. Increased concentrations above 3 nM do not further enhance this cardioprotective effect. This cardioprotective effect is independent of time point and length of application in the reperfusion period.

Activation of Melatonin Receptors by Ramelteon Induces Cardioprotection by Postconditioning in the Rat Heart

Activation of melatonin receptors protects the heart against ischemia-reperfusion injury. Ramelteon, a clinically used drug for insomnia, acts via activation of melatonin receptors. We investigated whether ramelteon induces acute infarct size reduction by postconditioning. Male Wistar rats were randomized to 6 groups. Hearts were treated with melatonin and ramelteon at the beginning of reperfusion. The melatonin receptor inhibitor luzindole was administered with and without melatonin and ramelteon, respectively. Ramelteon reduced infarct size to the same extent as melatonin. Both effects were completely abolished by luzindole. The results show for the first time that ramelteon induces cardioprotection by postconditioning.

Haemotherapy with Fibrinogen for Perioperative Bleeding Prevention-A View on Arterial Thrombogenesis and Myocardial Infarction in the Rat In Vivo

Major blood loss during cardiac surgery is associated with increased morbidity and mortality. Clinical pilot studies indicated that preoperative fibrinogen supplementation reduces postoperative blood loss without increasing thrombotic complications. However, an increase in fibrinogen concentration might rather aggravate pre-existing thrombosis than increase the incidence of thrombotic events. Therefore, we investigated, in the present study, whether fibrinogen supplementation influences (1) arterial thrombus formation, (2) the extent of myocardial infarction and (3) the cardioprotective effect of ischaemic preconditioning. Arterial thrombogenesis of the femoral artery was induced by topic FeCl₃ treatment in anaesthetised Wistar rats after pretreatment with 60 mg/kg (Fib_low), 120 mg/kg (Fib_high) or vehicle (Con). Vessel blood flow was monitored, and time to vessel occlusion was analysed as a marker for arterial thrombogenesis. In addition, regional myocardial I/R injury was induced by temporary left coronary artery occlusion in rats pretreated with or without fibrinogen supplementation. In additional groups, ischaemic preconditioning (IPC) was induced by 3 cycles of 5 min of ischaemia/reperfusion. In all groups, myocardial infarct size was determined by triphenyltetrazoliumchlorid staining. Arterial thrombogenesis was not affected by fibrinogen pretreatment. No differences in time until vessel occlusion between Con, Fib_low and Fib_high groups were observed. In addition, fibrinogen supplementation in low and high concentrations had no effect on infarct size after regional myocardial ischaemia and reperfusion (Fib_low: 66 ± 10%, Fib_high: 62 ± 9%; each ns vs. Con). IPC reduced infarct size from 62 ± 14% to 34 ± 12% (p < 0.05 vs. Con). Furthermore, both fibrinogen concentrations did not affect cardioprotection by ischaemic preconditioning (Fib_low + IPC: 34 ± 11%, Fib_high + IPC: 31 ± 13%; each ns vs. IPC). Haemotherapy with fibrinogen did not affect arterial thrombogenesis, myocardial infarction and the cardioprotective effect of ischaemic preconditioning.

Impact of Anesthetic Regimen on Remote Ischemic Preconditioning in the Rat Heart In Vivo

Remote ischemic preconditioning (RIPC) seems to be a promising cardioprotective strategy with contradictive clinical data suggesting the anesthetic regimen influencing the favorable impact of RIPC. This study aimed to investigate whether cardio protection by RIPC is abolished by anesthetic regimens. Male Wistar rats were randomized to 6 groups. Anesthesia was either maintained by pentobarbital (Pento) alone or a combination of sevoflurane (Sevo) and remifentanil or propofol (Prop) and remifentanil in combination with and without RIPC. RIPC reduced infarct size in Pento- and Sevo-anesthetized rats (Pento-RIPC: 30% ± 9% versus Pento-control [Con]: 65% ± 6%, P < .001; Sevo-RIPC: 31% ± 6% versus Sevo-Con: 61% ± 8%, P < .001), but RIPC did not initiate cardio protection in Prop-anesthetized animals (Prop-RIPC: 59% ± 6% versus Prop-Con: 59% ± 8%, P = 1.000). Cardio protection by RIPC is abolished by Prop.

Milrinone-Induced Pharmacological Preconditioning in Cardioprotection: Hints for a Role of Mitochondrial Mechanisms

The activation of mitochondrial calcium-sensitive potassium (mBK_Ca) channels is crucially involved in cardioprotection induced by preconditioning. For milrinone (Mil)-induced preconditioning, the involvement of mBK_Ca-channels and further mitochondrial signaling is unknown. We hypothesize that (1) Mil-induced preconditioning is concentration-dependent and (2) that the activation of mBK_Ca-channels, release of reactive oxygen species (ROS), and the mitochondrial permeability transition pore (mPTP) could be involved. Isolated hearts of male Wistar rats were perfused with Krebs-Henseleit buffer and underwent 33 min of ischemia followed by 60 min of reperfusion. For determination of a concentration-dependent effect of Mil, hearts were perfused with different concentrations of Mil (0.3–10 µM) over 10 min before ischemia. In a second set of experiments, in addition to controls, hearts were pretreated with the lowest protective concentration of 1 µM Mil either alone or combined with the mBK_Ca-channel blocker paxilline (Pax + Mil), or paxilline alone (Pax). In additional groups, Mil was administered with and without the ROS scavenger N-2-mercaptopropionylglycine (MPG + Mil, MPG) or the mPTP inhibitor cyclosporine A (MPG + Mil + CsA, CsA + Mil), respectively. Infarct sizes were determined by triphenyltetrazolium chloride (TTC) staining. The lowest and most cardioprotective concentration was 1 µM Mil (Mil 1: 32 ± 6%; p < 0.05 vs. Con: 63 ± 8% and Mil 0.3: 49 ± 6%). Pax and MPG blocked the infarct size reduction of Mil (Pax + Mil: 53 ± 6%, MPG + Mil: 59 ± 7%; p < 0.05 vs. Mil: 34 ± 6%) without having an effect on infarct size when administered alone (Pax: 53 ± 7%, MPG: 58 ± 5%; ns vs. Con). The combined administration of CsA completely restored the MPG-inhibited cardioprotection of Mil (MPG + Mil + CsA: 35 ± 7%, p < 0.05 vs. MPG + Mil). Milrinone concentration-dependently induces preconditioning. Cardioprotection is mediated by the activation of mBK_Ca-channels, release of ROS and mPTP inhibition.

Impact of Anesthetics on Cardioprotection Induced by Pharmacological Preconditioning

Anesthetics, especially propofol, are discussed to influence ischemic preconditioning. We investigated whether cardioprotection by milrinone or levosimendan is influenced by the clinically used anesthetics propofol, sevoflurane or dexmedetomidine. Hearts of male Wistar rats were randomised, placed on a Langendorff system and perfused with Krebs–Henseleit buffer (KHB) at a constant pressure of 80 mmHg. All hearts underwent 33 min of global ischemia and 60 min of reperfusion. Three different anesthetic regimens were conducted throughout the experiments: propofol (11 μM), sevoflurane (2.5 Vol%) and dexmedetomidine (1.5 nM). Under each anesthetic regimen, pharmacological preconditioning was induced by administration of milrinone (1 μM) or levosimendan (0.3 μM) 10 min before ischemia. Infarct size was determined by TTC staining. Infarct sizes in control groups were comparable (KHB-Con: 53 ± 9%, Prop-Con: 56 ± 9%, Sevo-Con: 56 ± 8%, Dex-Con: 53 ± 9%; ns). Propofol completely abolished preconditioning by milrinone and levosimendan (Prop-Mil: 52 ± 8%, Prop-Lev: 52 ± 8%; ns versus Prop-Con), while sevoflurane did not (Sevo-Mil: 31 ± 9%, Sevo-Lev: 33 ± 7%; p < 0.05 versus Sevo-Con). Under dexmedetomidine, results were inconsistent; levosimendan induced infarct size reduction (Dex-Lev: 36 ± 6%; p < 0.05 versus Dex-Con) but not milrinone (Dex-Mil: 51 ± 8%; ns versus Dex-Con). The choice of the anesthetic regimen has an impact on infarct size reduction by pharmacological preconditioning.

Cardioprotective Properties of Omecamtiv Mecarbil against Ischemia and Reperfusion Injury

Omecamtiv mecarbil (OM) is a first-in-class myosin activator. It was developed as a new inotropic therapy option for heart failure and is currently the object of a phase 3 clinical trial program. OM activates ryanodine receptors, which were shown to be involved in cardioprotection induced by conditioning strategies. We hypothesize that OM exerts a concentration-dependent cardioprotective effect through pre- and postconditioning. Isolated male Wistar rat hearts underwent 33 min of global ischemia and 60 min of reperfusion. OM was administered in various concentrations (1, 3, 10, and 30 µM) over 10 min prior to ischemia. Based on these results, in subsequent experiments 3 and 10 µM OM were given over 10 min after ischemia. Infarct sizes were determined by TTC staining. In controls, the infarct size was 60% ± 10% and 59% ± 12%, respectively. Ten micromolar OM before ischemia reduced the infarct size to 33% ± 8%. The lower concentrations did not initiate cardioprotection, and the next highest concentration did not enhance the protective effect. Even if 10 μM OM was given in the early reperfusion phase, it significantly reduced the infarct size (31% ± 6%), whereas 3 μM OM did not trigger a protective effect (58% ± 15%). This study shows for the first time that OM induces cardioprotection by pre- and postconditioning with a binary phenomenon, which is either ineffective or has a maximal effect.

European Society of Anaesthesiology Task Force on Nitrous Oxide: a narrative review of its role in clinical practice

Nitrous oxide (N₂O) is one of the oldest drugs still in use in medicine. Despite its superior pharmacokinetic properties, controversy remains over its continued use in clinical practice, reflecting in part significant improvements in the pharmacology of other anaesthetic agents and developing awareness of its shortcomings. This narrative review describes current knowledge regarding the clinical use of N₂O based on a systematic and critical analysis of the available scientific literature. The pharmacological properties of N₂O are reviewed in detail along with current evidence for the indications and contraindications of this drug in specific settings, both in perioperative care and in procedural sedation. Novel potential applications for N₂O for the prevention or treatment of chronic pain and depression are also discussed. In view of the available evidence, we recommend that the supply of N₂O in hospitals be maintained while encouraging its economic delivery using modern low flow delivery systems. Future research into its potential novel applications in prevention or treatment of chronic conditions should be pursued to better identify its role place in the developing era of precision medicine.

Milrinone-Induced Postconditioning Requires Activation of Mitochondrial Ca2+-sensitive Potassium (mBKCa) Channels

OBJECTIVES

Cardioprotection by postconditioning requires activation of mitochondrial large-conductance Ca2+-sensitive potassium (mBKCa) channels. The involvement of these channels in milrinone-induced postconditioning is unknown. The authors determined whether cardioprotection by milrinone-induced postconditioning involves activation of mBKCa channels in the rat heart in vitro.

DESIGN

Randomized, prospective, blinded laboratory investigation.

SETTING

Experimental laboratory.

PARTICIPANTS

Male Wistar rats.

INTERVENTIONS

Hearts of male Wistar rats were randomized, placed on a Langendorff system, and perfused with Krebs-Henseleit buffer at a constant pressure of 80 mmHg. All hearts were subjected to 33 minutes of global ischemia and 60 minutes of reperfusion. At the onset of reperfusion, hearts were perfused with different concentrations of milrinone (0.3-100 μM) for determination of a dose-effect curve. In a second set of experiments, 3 μM milrinone was administered in combination with the mBKCa channel inhibitor paxilline (1 μM). Infarct size was determined by triphenyltetrazoliumchloride staining.

MEASUREMENTS AND MAIN RESULTS

In control animals, infarct size was 37 ± 7%. Milrinone at a concentration of 3 μM reduced infarct size to 22 ± 7% (p < 0.05 v control). Higher milrinone concentrations did not confer stronger protection. Paxilline completely blocked milrinone-induced cardioprotection whereas paxilline alone had no effect on infarct size.

CONCLUSIONS

This study shows that activation of mBKCa channels plays a pivotal role in milrinone-induced postconditioning.