Comparaison de l'influence des valves "stentless" versus "stented" sur le remodelage ventriculaire gauche et la réserve coronaire, évaluées à 6 mois par IRM, dans le rétrécissement aortique serré

ANGERS-BU Médecine-Pharmacie (490072105) / SudocPARIS-BIUM (751062103) / SudocSudocFranceF

Heterogeneities in local plastic flow behavior in a dissimilar weld between low-alloy steel and stainless steel

In dissimilar welds between low-alloy steel and stainless steel, the post-weld heat-treatment results in a high variety of microstructures coexisting around the fusion line, due to carbon diffusion and carbides dissolution/precipitation. The local constitutive laws in the vicinity of the fusion zone were identified by micro tensile specimens for the sub-millimeter sized zones, equivalent bulk materials representing the decarburized layer using both wet H2 atmosphere and diffusion couple, and nano-indentation for the carburized regions (i.e. the martensitic band and the austenitic region). The decarburized zone presents only 50% of the yield strength of the low-alloy steel heat affected zone and a ductility doubled. The carburized zones have a yield strength 3–5 times higher than that of the low-alloy steel heat affected zone and have almost no strain hardening capacity. These properties result in heterogeneous plastic deformation happening over only millimeters when the weld is loaded perpendicularly to the weld line, affecting its overall behavior. The constitutive laws experimentally identified were introduced as inputs into a finite elements model of the transverse tensile test performed on the whole dissimilar weld. A good agreement between experiments and simulations was achieved on the global stressstrain curve. The model also well predicts the local strain field measured by microscale DIC. A large out-of-plane deformation due to the hard carburized regions has also been identified

A randomized study of defibrillator lead implantations in the right ventricular mid-septum versus the apex: the SEPTAL study.

International audienceINTRODUCTION: The study was designed to evaluate the feasibility and performance of right ventricular (RV) mid-septal versus apical implantable defibrillator (ICD) lead placement. METHODS AND RESULTS: SEPTAL is a randomized, noninferiority trial, which randomly assigned patients to implantation of ICD leads in the RV mid-septum versus apex, with a primary objective of comparing the implant success rate of implant at each site, based on strict electrical predefined criteria. We also compared the (1) pacing lead characteristics, (2) rates of appropriate and inappropriate ICD therapies, and (3) all-cause mortality between the 2 sites at 1 year. The trial enrolled 215 patients (mean age = 59.7 ± 12.4 years, mean LVEF = 34.0 ± 14.2%, 84.2% men), of whom 148 (68.8%) presented with ischemic heart disease. The ICD indication was primary prevention in 117 patients (54.4%). The lead was successfully implanted in 96/107 patients (89.7%) assigned to the RV mid-septum, and in 99/108 (91.7%) assigned to the apex (ns). The 1-year rate of lead-related adverse events was similar in both groups. A total of 8 first inappropriate ICD therapies (7.9%) were delivered in the RV mid-septal group, versus 8 (7.8%) in the apical group (ns), while first appropriate therapies were delivered to 22 (21.4%) and 24 patients (23.8%), respectively (ns). All-cause mortality was 7.9% in the RV mid-septal versus 2.9% in the RV apical group (ns). CONCLUSION: This study confirmed the technical feasibility and noninferior performance of ICD leads implanted in the RV mid-septum versus the apex