Lars Bergmann

Protection by remote ischemic preconditioning during coronary artery bypass graft surgery with isoflurane but not propofol – a clinical trial

Remote ischemic preconditioning (RIPC) of the myocardium by limb ischemia/reperfusion may mitigate cardiac damage, but its interaction with the anesthetic regimen is unknown. We tested whether RIPC is associated with differential effects depending on background anesthesia. Specifically, we hypothesized that RIPC during isoflurane anesthesia attenuates myocardial injury in patients undergoing coronary artery bypass graft (CABG) surgery, and that effects may be different during propofol anesthesia.

Cerebral Embolization During Transcatheter Aortic Valve Implantation A Transcranial Doppler Study

Background— Transcatheter aortic valve implantation (TAVI) is associated with a higher risk of neurological events for both the transfemoral and transapical approach than surgical valve replacement. Cerebral magnetic resonance imaging has revealed more new, albeit clinically silent lesions from procedural embolization, yet the main source and predominant procedural step of emboli remain unclear. Methods and Results— Eighty-three patients underwent transfemoral (Medtronic CoreValve [MCVTF], n=32; Edwards Sapien [ESTF], n=26) and transapical (ESTA: n=25) TAVI. Serial transcranial Doppler examinations before, during, and 3 months after TAVI were used to identify high-intensity transient signals (HITS) as a surrogate for microembolization. Procedural HITS were detected in all patients, predominantly during manipulation of the calcified aortic valve while stent valves were being positioned and implanted. The balloon-expandable ES prosthesis caused significantly more HITS (mean [95% CI]) during positioning (ESTF, 259.9 [184.8–334.9]; ESTA, 206.1[162.5–249.7]; MCVTF, 78.5 [25.3–131.6]; P<0.001) and the self-expandable MCV prosthesis during implantation (MCVTF, 397.1 [302.1–492.2]; ESTF, 88.2 [70.2–106.3]; ESTA, 110.7 [82.0–139.3]; P<0.001). Overall, there were no significant differences between transfemoral and transapical TAVI or between the MCV and ES prostheses. No HITS were detected at baseline or 3-month follow-up. There was 1 major procedural stroke that resulted in death and 1 minor procedural stroke with full recovery at 3-month follow-up in the MCV group. Conclusions— Procedural HITS were detected by transcranial Doppler in all patients. Although no difference was observed between the transfemoral and the transapical approach with the balloon-expandable ES stent valve, transfemoral TAVI with the self-expandable MCV prosthesis resulted in the greatest number of HITS, predominantly during implantation.

Transfemoral aortic valve implantation under sedation and monitored anaesthetic care--a feasibility study.

Surgical aortic valve replacement is the conventional treatment for symptomatic aortic valve stenosis; however, the technique of transfemoral transcatheter aortic valve implantation has recently been developed for older patients at high risk for surgery. We assessed whether this procedure could be safely performed under sedation in 100 patients. Their predicted surgical mortality was 21.6% and mean (SD) age 80 (6.6) years. Sedation was provided by remifentanil infusion (0–0.2u2003μg.kg−1.min−1) and midazolam (1–3u2003mg), as required. All patients were closely haemodynamically monitored throughout by an anaesthetist and inotropic drugs administered as indicated by invasive monitoring. Sedation alone was required in 83 patients; in 17 patients sedation had to be converted to general anaesthesia, mainly because of interventional complications (nu2003=u200312). All conversions to general anaesthesia occurred after successful valve implantation. Mean (SD) anaesthesia time was 31 (12) min and procedural time 107 (77)u2003min; 30‐day and 1‐year all‐cause mortality were 6% and 13%, respectively. In the majority of patients, transcatheter valve implantation can safely be facilitated by sedation, provided monitoring and drug administration are carried out by an experienced cardiac anaesthetist.

Coagulation management in patients undergoing mechanical circulatory support.

The incidence of bleeding and thrombo-embolic complications in patients undergoing mechanical circulatory support therapy remains high and is associated with bad outcomes and increased costs. The need for anticoagulation and anti-platelet therapy varies widely between different pulsatile and non-pulsatile ventricular-assist devices (VADs) and extracorporeal membrane oxygenation (ECMO) systems. Therefore, a unique anticoagulation protocol cannot be recommended. Notably, most thrombo-embolic complications occur despite values of conventional coagulation tests being within the targeted range. This is due to the fact that conventional coagulation tests such as international normalised ratio (INR), activated partial thromboplastin time (aPTT) and platelet count cannot detect hyper- or hypofibrinolysis, hypercoagulability due to tissue factor expression on circulating cells or increased clot firmness, and platelet aggregation as well as response to anti-platelet drugs. By contrast, point-of-care (POC) whole blood viscoelastic tests (thromboelastometry/-graphy) and platelet function tests (impedance or turbidimetric aggregometry) reflect in detail the haemostatic status of patients undergoing mechanical circulatory support therapy and the efficacy of their anticoagulation and antiaggregation therapy. Therefore, monitoring of haemostasis using POC thromboelastometry/-graphy and platelet function analysis is recommended during mechanical circulatory support therapy to reduce the risk of bleeding and thrombo-embolic complications. Notably, these haemostatic tests should be performed repeatedly during mechanical circulatory support therapy since thrombin generation, clot firmness and platelet response may change significantly over time with a high inter- and intra-individual variability. Furthermore, coagulation management can be hampered in non-pulsatile VADs by acquired von Willebrand syndrome, and in general by acquired factor XIII deficiency as well as by heparin-induced thrombocytopenia. In addition, POC testing can be used in bleeding patients to guide calculated goal-directed therapy with allogeneic blood products, haemostatic drugs and coagulation factor concentrates to optimise the haemostasis and to minimise transfusion requirements, transfusion-associated adverse events and to avoid thrombo-embolic complications, as well. However, coagulation management in patients undergoing mechanical circulatory support therapy is somehow like navigating between Scylla and Charybdis, and development of protocols based on POC testing seems to be beneficial.

A novel functional haplotype in the human GNAS gene alters Gαs expression, responsiveness to β-adrenoceptor stimulation, and peri-operative cardiac performance

AIMSnCardiac overexpression of the beta-adrenoceptor-coupled G-protein subunit Galphas in mice enhances inotropic responses to sympathetic stimulation, but evokes cardiomyopathy with increasing age. We tested whether functional single nucleotide polymorphisms (SNPs) in the human Galphas (GNAS) gene modulate Galphas expression and assessed functional consequences.nnnMETHODS AND RESULTSnSequencing the promoter and intron 1 of GNAS revealed 11 SNPs resulting in three common haplotypes. Haplotype *3 constructs exhibited significantly higher promoter activity than haplotypes *1 and *2, resulting in a more than 50% higher Galphas mRNA expression in homozygous *3 carriers (*3/*3) than in heterozygous (*3/-) and negative *3 (-/-) carriers (P = 0.002). Basal, Galphas- (via NaF and GTP) and isoproterenol-stimulated adenylyl cyclase (AC) activities were also significantly higher in *3/*3 than in *3/- and -/- carriers. In contrast, direct AC activation via forskolin was independent of GNAS haplotypes. Furthermore, haemodynamic measurements in 137 coronary artery bypass patients revealed a higher cardiac index in *3/*3 carriers than in *3/- and -/- carriers (P = 0.025) associated with a lower NYHA functional class (P = 0.040) and serum NT-proBNP concentrations (P = 0.002).nnnCONCLUSIONnSNPs in regulatory regions of GNAS impact upon Galphas expression and stimulated cAMP formation in human hearts in vitro and upon cardiac performance in vivo.

Uneventful Removal of an Epidural Catheter Guided by Impedance Aggregometry in a Patient With Recent Coronary Stenting and Treated With Clopidogrel and Acetylsalicylic Acid

Objective: This report suggests that impedance aggregometry can be helpful to assess optimum time for and minimize the risk of catheter removal during double antiplatelet therapy. Case Report: A 52-year-old patient undergoing cystectomy during combined general and epidural anesthesia suffered an acute myocardial infarction, and required coronary artery stenting and dual antiplatelet function therapy. Conclusions: Balancing the risks of stent occlusion and epidural bleeding, bedside impedance aggregometry helped to identify the optimum time window for epidural catheter removal with the lowest bleeding risk in this patient.

Incidence, predictors, origin and prevention of early and late neurological events after transcatheter aortic valve implantation (TAVI): a comprehensive review of current data

Transcatheter aortic valve implantation (TAVI) is a novel treatment option for patients with severe, symptomatic aortic valve stenosis considered inoperable or at high risk for surgical aortic valve replacement. Despite rapid adoption of this technology into clinical application, however, recent randomized controlled clinical trials have raised safety concerns regarding an increased risk of neurological events with TAVI compared to both medical treatment and conventional, surgical aortic valve replacement. Moreover, neuro-imaging studies have revealed an even higher incidence of new, albeit clinically silent cerebral lesions as a surrogate for procedural embolization. In this article, we review currently available data on the incidence, timing, predictors, prognostic implications and potential mechanisms of neurological events after TAVI.

Phrenic nerve block caused by interscalene brachial plexus block: breathing effects of different sites of injection

BackgroundInterscalene brachial plexus (ISB) block is often associated with phrenic nerve block and diaphragmatic paresis. The goal of our study was to test if the anterior or the posterior ultrasound guided approach of the ISB is associated with a lower incidence of phrenic nerve blocks and impaired lung function.MethodsThis was a prospective, randomized and single-blinded study of 84 patients scheduled for elective shoulder surgery who fullfilled the inclusion and exclusion critereria. Patients were randomized in two groups to receive either the anterior (nu2009=u200942) or the posterior (nu2009=u200942) approach for ISB. Clinical data were recorded. In both groups patients received ISB with a total injection volume of 15xa0ml of ropivacaine 1xa0%. Spirometry was conducted at baseline (T0) and 30xa0min (T30) after accomplishing the block.Changes in spirometrical variables between T0 and T30 were investigated by Wilcoxon signed-rank test for each puncture approach. The temporal difference between the posterior and the anterior puncture approach groups were again analyzed by the Wilcoxon-Mann-Whitney test.ResultsThe spirometric results showed a significant decrease in vital capacity, forced expiratory volume per second, and maximum nasal inspiratory breathing after the Interscalene brachial plexus block; indicating a phrenic nerve block (p <0.001, Wilcoxon signed-rank). A significant difference in the development of the spirometric parameters between the anterior and the posterior group could not be identified (Wilcoxon-Mann-Whitney test). Despite the changes in spirometry, no cases of dyspnea were reported.ConclusionA different site of injection (anterior or posterior) did not show an effect in reducing the cervical block spread of the local anesthetic and the incidence of phrenic nerve blocks during during ultrasound guided Interscalene brachial plexus block. Clinical breathing effects of phrenic nerve blocks are, however, usually well compensated, and subjective dyspnea did not occur in our patients.Trial registrationGerman Clinical Trials Register (DRKS number 00009908, registered 26 January 2016).

Arrhythmogenic risk of pulmonary artery catheterisation in patients with severe aortic stenosis undergoing transcatheter aortic valve implantation

Many clinicians consider severe aortic stenosis to be a contraindication to pulmonary artery catheterisation, except during open heart surgery with cardiopulmonary bypass. This is due to the perceived high risk of arrhythmia, although the true incidence of ventricular tachycardia and fibrillation remains unclear. We conducted a retrospective study to estimate the incidence of severe arrhythmias during pulmonary artery catheterisation in 380 patients with severe aortic stenosis scheduled for transcatheter aortic valve implantation. Ventricular fibrillation was seen in only one patient (0.26%), and this was successfully terminated by external defibrillation. No episodes of ventricular tachycardia were recorded and there were also no arrhythmias during removal of the catheter. We have therefore concluded that pulmonary artery catheterisation in patients with severe aortic stenosis is not associated with a high incidence of ventricular fibrillation or tachycardia, allowing pulmonary artery pressure monitoring to be performed relatively safely in such patients.

Anesthesia with transfemoral and transapical aortic valve implantation. Periinterventional management and hemodynamic observations

Percutaneous transfemoral and transapical aortic valve implantations are novel procedures that often confront the anesthesiologist with bigger challenges than surgical aortic valve replacements using cardiopulmonary bypass. Due to old age and the presence of severe comorbidities including pulmonary vascular hypertension, most patients have a very high risk. Individual comorbidities and their severity are as important for the choice of the anesthetic technique as pharmacological cardiovascular therapy and communication during the respective phases of the intervention. Since severe hemodynamic alterations (cardiogenic shock, coronary ischemia, arrhythmias) and potential interventional complications (bleeding, ventricular and vascular injury) may occur, the authors routinely perform an extended cardiovascular monitoring. General endotracheal anesthesia may be advantageous even for transfemoral valve implantation and was not associated with a worse outcome. Following valve implantation a substantial increase in cardiac index, but also of all filling pressures was measured. Anesthesia coverage time for the first 100 cases averaged 263 min (+/- 96) for transfemoral and 297 (+/- 78) for transapical valve implantation, which appears greater than for conventional aortic valve replacement surgery, but it decreased significantly for transfemoral valve implantation over the course of interventions. Accordingly, the anesthesiologist, besides providing anesthesia and managing the airway, assumes responsibility for invasive cardiopulmonary monitoring, cardiovascular pharmacotherapy tailored to intervention phases, and troubleshooting in the event of complications for these still developing interventions.ZusammenfassungTransfemorale (TF) und transapikale (TA) Aortenklappenimplantationen sind neue interventionelle Verfahren, die den Anästhesiologen allerdings oft vor größere Herausforderungen stellen als klassische Operationen unter kardiopulmonalem Bypass. Beim gegenwärtigen Indikationsspektrum handelt es sich nämlich um zumeist hochbetagte Patienten mit erheblicher Komorbidität, pulmonalvaskulärer Hypertonie und sehr hohem operativen Risiko.Art und Umfang individueller Komorbidität sind bei der Wahl des Anästhesieverfahrens (Intubationsanästhesie vs. Stand-by/Analgosedierung) ebenso wichtig wie interventionsphasenspezifische Kreislauftherapie und interdisziplinäre Kommunikation. Ein Allgemeinanästhesieverfahren auch bei der TFAortenklappenimplantation ist in vielerlei Hinsicht von Vorteil und scheint nicht zu schlechteren Ergebnissen zu führen. Aufgrund möglicher gravierender hämodynamischer Alterationen (kardiogener Schock, Koronarischämie, Arrhythmien) sowie interventioneller Komplikationen (Blutung, Ventrikelverletzung, Gefäßverletzung) verwenden die Autoren routinemäßig eine erweiterte invasive Kreislaufüberwachung. Postinterventionell wurde eine deutliche signifikante Zunahme des Herzindex, aber auch aller Füllungsdrücke beobachtet. Die periinterventionelle Anästhesiebindungszeit bei den ersten 100 Interventionen betrug 263 min (± 96) bei TF und 297 min (± 78) bei TA, erscheint damit eher höher als bei offener Aortenklappenimplantation, nahm jedoch bei TF im Verlauf signifikant ab.Entsprechend spielt der Anästhesiologe bei diesen sicher noch entwicklungsfähigen Verfahren eine wichtige Rolle für die invasive kardiopulmonale Überwachung, interventionsphasenorientierte kardiovaskuläre Pharmakotherapie sowie „troubleshooting“ bei Komplikationen.AbstractPercutaneous transfemoral and transapical aortic valve implantations are novel procedures that often confront the anesthesiologist with bigger challenges than surgical aortic valve replacements using cardiopulmonary bypass. Due to old age and the presence of severe comorbidities including pulmonary vascular hypertension, most patients have a very high risk.Individual comorbidities and their severity are as important for the choice of the anesthetic technique as pharmacological cardiovascular therapy and communication during the respective phases of the intervention. Since severe hemodynamic alterations (cardiogenic shock, coronary ischemia, arrhythmias) and potential interventional complications (bleeding, ventricular and vascular injury) may occur, the authors routinely perform an extended cardiovascular monitoring. General endotracheal anesthesia may be advantageous even for transfemoral valve implantation and was not associated with a worse outcome. Following valve implantation a substantial increase in cardiac index, but also of all filling pressures was measured. Anesthesia coverage time for the first 100 cases averaged 263 min (± 96) for transfemoral and 297 (± 78) for transapical valve implantation, which appears greater than for conventional aortic valve replacement surgery, but it decreased significantly for transfemoral valve implantation over the course of interventions.Accordingly, the anesthesiologist, besides providing anesthesia and managing the airway, assumes responsibility for invasive cardiopulmonary monitoring, cardiovascular pharmacotherapy tailored to intervention phases, and „troubleshooting“ in the event of complications for these still developing interventions.