Evaluierung eines Neurostent-Prototyps am experimentellen Aneurysma-Modell

The occurrence of a subarachnoid hemorrhage (SAH) is a life-threatening disease, which is accompanied with a very high rate of morbidity and mortality. The main cause of a non-traumatic SAH is a ruptured cerebral artery aneurysm, which primarily leads to a bleeding into the arachnoid cisterns of the brain. In spite of this positive trend in the area of new endovascular materials and techniques, certain intracranial aneurysms still prevent the application of this minimal invasive therapy. A first promising approach to this problem lies in the application of a vascular stent in combination with a platinum coil to allow a permanent occlusion of the broad-based aneurysms. With the use of these stents a more sealing embolization, a faster and better thrombosis of the aneurysm as well as a modulation of the blood flow in the parent vessel should be achieved. This thesis examines the application of an electrolytically detachable and completely repositionable stent prototype as a therapy for broad-based intracranial aneurysms by the utilisation of an elastase-induced aneurysm model in 12 rabbits. For the evaluation of this novel system the stent was implanted and the aneurysm was subsequent embolized with conventional coils. A final examination after three month was accomplished by the use of MRT, CT, DSA and histology. The stent presented itself as a flexible and easy to navigate implant. In every case the positioning and repositioning was possible without any complications. During the intervention and all along the examination time its radial forces lead to an adequate vascular adaptation without any deformation of the vessel. The functional mesh-design allowed a flawless probing of the aneurysms with the micro-catheter. The stent served as a bearing for the coil-package and prevented a protrusion. The three imaging methods allowed an evaluation of the interesting parameters: In 11 of 12 cases the aneurysms showed a very good occlusion, in all cases the long-term patency of the stent was present and finally no recanalisation occurred. The stent fulfilled the requirement of being highly bio-compatible. However, regarding the material, difficulties in form of stent breakage and in association with the detaching mechanism emerged. Only with 2 animals the number of detaching attempts satisfied the expectations. If the recovered shortcomings will be eliminated, the acquired data and results within this thesis are promising an efficient and effective application of the prototype for the therapy of broad-based aneurysms. Despite the restrictions regarding the transferability of data gathered by animal experiments to the intracranial, human situation, the obtained results could be the basis for a clinical adoption of this novel stent system in human patients.Die Subarachnoidalblutung ist eine lebensbedrohliche Erkrankung, die mit einer sehr hohen Morbidität und Mortalität einhergeht. Die Hauptursache einer nicht-traumatischen SAB ist ein geplatztes Hirnarterienaneurysma, das vorrangig zu Blutungen in die arachnoidalen Zisternen des Gehirns führt. Trotz der positiven Entwicklungen neuer endovaskulärer Materialien und Methoden, entziehen sich bestimmte intrakranielle Aneurysmen weiterhin der minimal-invasiven Therapie. Erfolgversprechende erste Lösungsansätze auf dem Gebiet breitbasiger Hirnaneurysmen sind der Einsatz spezieller Gefäßstützen (Stents), die in Kombination mit Platinspiralen (Coils) einen dauerhaften Verschluss breitbasiger Aneurysmen erlauben sollen. Mit Hilfe der Stents soll eine dichtere Embolisation, eine schnellere und bessere Thrombosierung des Aneurysmas sowie eine Modulation des Blutstroms im Trägergefäß erzielt werden. In der hier vorliegenden Arbeit wurde bei 12 Kaninchen ein elektrolytisch ablösbarer und vollständig replatzierbarer Neurostent-Prototyp zur Behandlung breitbasiger intrakranieller Aneurysmen am Elastase-induziertes Aneurysmamodell untersucht. Das neuartige Stentsystem wurde implantiert und das Aneurysma nachfolgend mit herkömmlichen Coils embolisiert. Die Handhabung des Stents wurde beurteilt und nach drei Monaten die MRT-, CT- und DSA- Abschlusskontrolle sowie die histologische Aufarbeitung durchgeführt. Der Stent stellte sich als flexibles, leicht navigierbares Implantat dar. Er ließ sich in allen Fällen komplikationslos positionieren und repositionieren. Seine Radialkräfte führten zu einer ausreichenden Wandadaption während der Intervention sowie über den gesamten Untersuchungszeitraum ohne eine Gefäßverformung zu verursachen. Das zweckmäßige Maschendesign erlaubte eine einwandfreie Sondierung der Aneurysmen mit dem Mikrokatheter. Der Stent diente den Coilpaketen als Widerlager und verhinderte deren Protrusion. Die drei bildgebenden Verfahren erlaubten eine Beurteilung der interessierenden Parameter: die Aneurysmen zeigten in 11 von 12 Fällen einen sehr guten Verschluss, die Langzeitdurchgängigkeit des Stents war in allen Fällen gegeben und es traten keine Rekanalisationen auf. Der Stent zeigte eine hohe Biokompatibilität. Hinsichtlich des Materials traten jedoch Schwierigkeiten in Form von Stentbrüchen und beim Ablösemechanismus auf. Die Anzahl der Ablöseversuche erfüllte lediglich bei 2 Tieren die Erwartungen. Die in dieser Arbeit erhobenen Daten und Erkenntnisse versprechen einen effizienten und erfolgreichen Einsatz des Prototyps zur Therapie breitbasiger Aneurysmen, sofern die gefundenen Schwierigkeiten ausgeschaltet werden. Trotz der Einschränkungen der Übertragbarkeit tierexperimentell gewonnener Daten auf die intrakranielle, humane Situation können die gewonnenen Ergebnisse die Grundlage für den klinischen Einsatz dieses neuartigen Stentsystems im Menschen darstellen

Towards real-time cardiovascular magnetic resonance guided transarterial CoreValve implantation: in vivo evaluation in swine

<p>Abstract</p> <p>Background</p> <p>Real-time cardiovascular magnetic resonance (rtCMR) is considered attractive for guiding TAVI. Owing to an unlimited scan plane orientation and an unsurpassed soft-tissue contrast with simultaneous device visualization, rtCMR is presumed to allow safe device navigation and to offer optimal orientation for precise axial positioning. We sought to evaluate the preclinical feasibility of rtCMR-guided transarterial aortic valve implatation (TAVI) using the nitinol-based Medtronic CoreValve bioprosthesis.</p> <p>Methods</p> <p>rtCMR-guided transfemoral (n = 2) and transsubclavian (n = 6) TAVI was performed in 8 swine using the original CoreValve prosthesis and a modified, CMR-compatible delivery catheter without ferromagnetic components.</p> <p>Results</p> <p>rtCMR using TrueFISP sequences provided reliable imaging guidance during TAVI, which was successful in 6 swine. One transfemoral attempt failed due to unsuccessful aortic arch passage and one pericardial tamponade with subsequent death occurred as a result of ventricular perforation by the device tip due to an operating error, this complication being detected without delay by rtCMR. rtCMR allowed for a detailed, simultaneous visualization of the delivery system with the mounted stent-valve and the surrounding anatomy, resulting in improved visualization during navigation through the vasculature, passage of the aortic valve, and during placement and deployment of the stent-valve. Post-interventional success could be confirmed using ECG-triggered time-resolved cine-TrueFISP and flow-sensitive phase-contrast sequences. Intended valve position was confirmed by ex-vivo histology.</p> <p>Conclusions</p> <p>Our study shows that rtCMR-guided TAVI using the commercial CoreValve prosthesis in conjunction with a modified delivery system is feasible in swine, allowing improved procedural guidance including immediate detection of complications and direct functional assessment with reduction of radiation and omission of contrast media.</p

Can the adenosine triphosphate (ATP) bioluminescence assay be used as an indicator for hospital cleaning? – A pilot study

Background: In hospital cleaning, there is currently no standard for uniform monitoring of surface cleaning, either in Germany or internationally. One possibility for monitoring is the use of so-called objective methods for checking cleaning performance (e.g. fluorescence or adenosine triphosphate (ATP) method).Aim: The aim of the study was to monitor and evaluate the implementation of the adenosine triphosphate (ATP) bioluminescence assay as a cleaning indicator in everyday hospital cleaning, in order to verify its utility and effectiveness.Methods: In three phases, five frequently touched surfaces were examined with the ATP bioluminescence assay at different time points. 846 measurements were performed on the dermatology ward of niversity hospital (phase 1), 1,350 measurements were performed on five different wards of the university hospital (phase 2), and 1,04easurements were performed on five wards of another large hospital (phase 3). For this purpose, one structurally old and one structurally new ward as well as an intensive care unit (ICU), an outpatient clinic and a radiology department were selected for phases 2 and 3.Results: With the ATP bioluminescence method, we were able to demonstrate a reduction in values after cleaning: before cleaning mean of ATP, 907 relative light units (RLU) (95% confidence interval [CI] 77,038); after cleaning mean=286 RLU (CI=233; 495) (phase 1) and by intervention (five hours after daily cleaning mean=360 RLU (CI=303; 428); five hours after daily cleaning and two additional cleanings mean=128 RLU (CI=107; 152) (phase 3). The ATP values increased five hours after cleaning in phases 1 and 2, and eight hours after cleaning in phase 3. The structurally old wards had the highest ATP content, the ICU and the radiology department, among others, the lowest. In all phases, door handles showed both a reduction after cleaning or intervention and a subsequent increase in ATP values. Chair armrests, examination tables and door handles had high ATP values overall.Conclusion: The study shows ward differences both for cleaning effects and for the soiling characteristics of surfaces during the course of the day. In addition, it demonstrates the benefit of intermediate cleaning twice a day. It is noteworthy that structurally old stations and older inventory were more heavily soiled and, in some cases, more difficult to clean. The results show that the ATP bioluminescence method is suitable for detecting cleaning effects and can be used in everyday clinical practice for simple cleaning monitoring. Furthermore, it enables the detection of risk surfaces and easy-to-clean surfaces with significant re-soiling

Legionella contamination of a cold-water supplying system in a German university hospital – assessment of the superheat and flush method for disinfection: Heat and flush disinfection for legionella contamination

Introduction: Legionella spp. is a potential pneumonia causing pathogen, which can be transmitted to humans from water-supplying systems. Immunocompromised but also healthy individuals can be vitally threatened. Both, hot and cold-water supplying systems must be considered as transmission sources and therefore a periodic surveillance has to be performed in public buildings according to local legislations. During a routine surveillance, a hazardous colonization was detected within the cold-water supplying system at University Hospital Knappschaftskrankenhaus Bochum, Germany. Applied architectural measures remained unsatisfying in the reduction of legionella contamination of the cold-water distributing system. Methods: Adapted to an analysis of risks, effort and benefit, the superheat and flush procedure was applied twice with a time interval of 6 months. Results were evaluated concerning the efficiency and the sustainability and statistically analyzed. Results: While 33 out of 70 samples had a higher legionella count than the legal threshold of 100 CFU/100 mL (CFU - Colony Forming Units) before the first disinfection was carried out, this number could be reduced to 1 out of 202 samples after the first intervention. Additionally, in contrast to previously published studies, the effect was long-lasting, as no relevant limit exceedance occurred during the following observation period of more than two years. Conclusion: The superheat and flush disinfection can provide an economic and highly effective measure in case of legionella contamination and should be shortlisted for an eradication attempt of affected water-supplying systems in hospitals

Monitoring of endoscope reprocessing with an adenosine triphosphate (ATP) bioluminescence method

Background: The arising challenges over endoscope reprocessing quality proposes to look for possibilities to measure and control the process of endoscope reprocessing.Aim: The goal of this study was to evaluate the feasibility of monitoring endoscope reprocessing with an adenosine triphosphate (ATP) based bioluminescence system.Methods: 60 samples of eight gastroscopes have been assessed from routine clinical use in a major university hospital in Germany. Endoscopes have been assessed with an ATP system and microbial cultures at different timepoints during the reprocessing. Findings: After the bedside flush the mean ATP level in relative light units (RLU) was 19,437 RLU, after the manual cleaning 667 RLU and after the automated endoscope reprocessor (AER) 227 RLU. After the manual cleaning the mean total viable count (TVC) per endoscope was 15.3 CFU/10 ml, and after the AER 5.7 CFU/10 ml. Our results show that there are reprocessing cycles which are not able to clean a patient used endoscope.Conclusion: Our data suggest that monitoring of flexible endoscope with ATP can identify a number of different influence factors, like the endoscope condition and the endoscopic procedure, or especially the quality of the bedside flush and manual cleaning before the AER. More process control is one option to identify and improve influence factors to finally increase the overall reprocessing quality, best of all by different methods. ATP measurement seems to be a valid technique that allows an immediate repeat of the manual cleaning if the ATP results after manual cleaning exceed the established cutoff of 200 RLU