Remote Inspection, Measurement and Handling for LHC

Personnel access to the LHC tunnel will be restricted to varying extents during the life of the machine due to radiation, cryogenic and pressure hazards. The ability to carry out visual inspection, measurement and handling activities remotely during periods when the LHC tunnel is potentially hazardous offers advantages in terms of safety, accelerator down time, and costs. The first applications identified were remote measurement of radiation levels at the start of shut-down, remote geometrical survey measurements in the collimation regions, and remote visual inspection during pressure testing and initial machine cool-down. In addition, for remote handling operations, it will be necessary to be able to transmit several real-time video images from the tunnel to the control room. The paper describes the design, development and use of a remotely controlled vehicle to demonstrate the feasibility of meeting the above requirements in the LHC tunnel. Design choices are explained along with operating experience to-date and future development plans

Collimateur integration and installation: Example of one object to be installed in the LHC

The collimation system is a vital part of the LHC project, protecting the accelerator against unavoidable regular and irregular beam loss. About 80 collimators will be installed in the machine before the first run. Two insertion regions are dedicated to collimation and these regions will be among the most radioactive in the LHC. The space available in the collimation regions is very restricted, it was therefore important to ensure that the 3-D integration of these areas of the LHC tunnel would allow straightforward installation of collimators and also exchange of collimators under the remote handling constraints imposed by high radiation levels. The paper describes the 3-D integration studies and verifications of the collimation regions combining the restricted space available, the dimensions of the different types of collimators and the space needed for transport and handling. The paper explains how installation has been planned and carried out taking into account the handling

Surgical Explantation After TAVR Failure: Mid-Term Outcomes From the EXPLANT-TAVR International Registry

Objectives: The aim of this study was to evaluate clinical characteristics, mechanisms of failure, and outcomes of transcatheter aortic valve replacement (TAVR) explantation. Background: Surgical explantation following TAVR may be required for structural valve degeneration, paravalvular leak, infection, or other reasons. However, in-depth data on indications and outcomes are lacking. Methods: Data from a multicenter, international registry (EXPLANT-TAVR) of patients who underwent TAVR explantation were reviewed retrospectively. Explantations performed during the same admission as initial TAVR were excluded. Clinical and echocardiographic outcomes were evaluated. Median follow-up duration was 6.7 months (interquartile range [IQR]: 1.0-18.8 months) after TAVR explantation and was 97.7% complete at 30 days and 86.1% complete at 1 year. Results: From November 2009 to September 2020, 269 patients across 42 centers with a mean age of 72.7 ± 10.4 years underwent TAVR explantation. About one quarter (25.9%) were deemed low surgical risk at index TAVR, and median Society of Thoracic Surgeons risk at TAVR explantation was 5.6% (IQR: 3.2%-9.6%). The median time to explantation was 11.5 months (IQR: 4.0-32.4 months). Balloon-expandable and self-expanding or mechanically expandable valves accounted for 50.9% and 49.1%, respectively. Indications for explantation included endocarditis (43.1%), structural valve degeneration (20.1%), paravalvular leak (18.2%), and prosthesis-patient mismatch (10.8%). Redo TAVR was not feasible because of unfavorable anatomy in 26.8% of patients. Urgent or emergency cases were performed in 53.1% of patients, aortic root replacement in 13.4%, and 54.6% had concomitant cardiac procedures. Overall survival at last follow-up was 76.1%. In-hospital, 30-day, and 1-year mortality rates were 11.9%, 13.1%, and 28.5%, respectively, and stroke rates were 5.9%, 8.6%, and 18.7%, respectively. Conclusions: The EXPLANT-TAVR registry reveals that surgical risks associated with TAVR explantation are not negligible and should be taken into consideration in the lifetime management of aortic stenosis