Valve-sparing aortic root replacement using the reimplantation (David) technique:a systematic review and meta-analysis on survival and clinical outcome

BACKGROUND: Current guidelines recommend valve-sparing aortic root replacement (VSRR) procedures over valve replacement for the treatment of root aneurysm. The reimplantation technique seems to be the most widely used valve-sparing technique, with excellent outcomes in mostly single-center studies. The aim of this systematic review and meta-analysis is to present a comprehensive overview of clinical outcomes after VSRR with the reimplantation technique, and potential differences for bicuspid aortic valve (BAV) phenotype. METHODS: We conducted a systematic literature search of papers reporting outcomes after VSRR that were published since 2010. Studies solely reporting on acute aortic syndromes or congenital patients were excluded. Baseline characteristics were summarized using sample size weighting. Late outcomes were pooled using inverse variance weighting. Pooled Kaplan-Meier (KM) curves for time-to-event outcomes were generated. Further, a microsimulation model was developed to estimate life expectancy and risks of valve-related morbidity after surgery. RESULTS: Forty-four studies, with 7,878 patients, matched the inclusion criteria and were included for analysis. Mean age at operation was 50 years and almost 80% of patients were male. Pooled early mortality was 1.6% and the most common perioperative complication was chest re-exploration for bleeding (5.4%). Mean follow-up was 4.8±2.8 years. Linearized occurrence rates for aortic valve (AV) related complications such as endocarditis and stroke were below 0.3% patient-year. Overall survival was 99% and 89% at 1- and 10-year respectively. Freedom from reoperation was 99% and 91% after 1 and 10 years, respectively, with no difference between tricuspid and BAVs. CONCLUSIONS: This systematic review and meta-analysis shows excellent short- and long-term results of valve-sparing root replacement with the reimplantation technique in terms of survival, freedom from reoperation, and valve related complications with no difference between tricuspid and BAVs

Propagation of back-arc extension into the arc lithosphere in the southern New Hebrides volcanic arc

New geophysical data acquired during three expeditions of the R/V Southern Surveyor in the southern part of the North Fiji Basin allow us to characterize the deformation of the upper plate at the southern termination of the New Hebrides subduction zone, where it bends eastward along the Hunter Ridge. Unlike the northern end of the Tonga subduction zone, on the other side of the North Fiji Basin, the 90° bend does not correspond to the transition from a subduction zone to a transform fault, but it is due to the progressive retreat of the New Hebrides trench. The subduction trench retreat is accommodated in the upper plate by the migration toward the southwest of the New Hebrides arc and toward the south of the Hunter Ridge, so that the direction of convergence remains everywhere orthogonal to the trench. In the back-arc domain, the active deformation is characterized by propagation of the back-arc spreading ridge into the Hunter volcanic arc. The N-S spreading axis propagates southward and penetrates in the arc, where it connects to a sinistral strike-slip zone via an oblique rift. The collision of the Loyalty Ridge with the New Hebrides arc, less than two million years ago, likely initiated this deformation pattern and the fragmentation of the upper plate. In this particular geodynamic setting, with an oceanic lithosphere subducting beneath a highly sheared volcanic arc, a wide range of primitive subduction-related magmas has been produced including adakites, island arc tholeiites, back-arc basin basalts, and medium-K subduction-related lavas

Identification of a Distal GLUT4 Trafficking Event Controlled by Actin Polymerization

The insulin-stimulated trafficking of GLUT4 to the plasma membrane in muscle and fat tissue constitutes a central process in blood glucose homeostasis. The tethering, docking, and fusion of GLUT4 vesicles with the plasma membrane (PM) represent the most distal steps in this pathway and have been recently shown to be key targets of insulin action. However, it remains unclear how insulin influences these processes to promote the insertion of the glucose transporter into the PM. In this study we have identified a previously uncharacterized role for cortical actin in the distal trafficking of GLUT4. Using high-frequency total internal reflection fluorescence microscopy (TIRFM) imaging, we show that insulin increases actin polymerization near the PM and that disruption of this process inhibited GLUT4 exocytosis. Using TIRFM in combination with probes that could distinguish between vesicle transport and fusion, we found that defective actin remodeling was accompanied by normal insulin-regulated accumulation of GLUT4 vesicles close to the PM, but the final exocytotic fusion step was impaired. These data clearly resolve multiple steps of the final stages of GLUT4 trafficking, demonstrating a crucial role for actin in the final stage of this process