Small balloon strategy associated with low pacemaker implantation rate after self-expanding transcatheter valve implantation

BACKGROUND: This study aims to investigate whether small balloon aortic valvuloplasty(BAV) reduces the need for permanent pacemaker implantation (PPMI) after transcatheter aortic valveimplantation (TAVI).METHODS: This was a retrospective analysis using data from our local TAVI database. SmallBAV was defined as a small balloon size (=18 mm) pre-dilatation. Normal BAV was defined as aballoon size >18 mm. The primary endpoint was the incidence of new PPMI.RESULTS: Of 99 consecutive TAVI patients, five patients were excluded due to pre-existingpermanent pacemaker. Patients in the small BAV group (n=57) had a signifi cantly lower PPMI ratecompared with the normal BAV group (n=37) (3.5% vs. 18.9%, P=0.026). Moderate or severe aorticvalve regurgitation post-procedure was similar between the small BAV and normal BAV groups (5.3%vs. 8.1%, P=0.480);likewise, the mean aortic gradient post-procedure did not differ significantly(11.5±5.2 mmHg vs. 12.2±7.3 mmHg, 1 mmHg=0.133 kPa, P=0.580) between the groups. Devicesuccess rates were also similar (94.7% vs. 91.8%, P=0.680). In multivariable analysis, small BAV(P=0.027), the ratio of prosthesis diameter to annulus diameter (P=0.048), and mean aortic gradientby echo in the basement (P=0.021) were independent predictors of PPMI.CONCLUSIONS: The small BAV strategy is associated with a low rate of permanentpacemaker implantation after transcatheter self-expanding valve implantation in this single-centerobservational study.

Optimized postconditioning algorithm protects liver graft after liver transplantation in rats

Background: Ischemia reperfusion injury(IRI) causes postoperative complications and influences the outcome of the patients undergoing liver surgery and transplantation. Postconditioning(Post C) is a known manual conditioning to decrease the hepatic IRI. Here we aimed to optimize the applicable Post C protocols and investigate the potential protective mechanism.Methods: Thirty Sprague–Dawley rats were randomly divided into 3 groups: the sham group(n = 5),standard orthotopic liver transplantation group(OLT, n = 5), Post C group(OLT followed by clamping and re-opening the portal vein for different time intervals, n = 20). Post C group was then subdivided into 4 groups according to the different time intervals:(10 s × 3, 10 s × 6, 30 s × 3, 60 s × 3, n = 5 in each subgroup). Liver function, histopathology, malondialdehyde(MDA), myeloperoxidase(MPO), expressions of p-Akt and endoplasmic reticulum stress(ERS) related genes were evaluated.Results: Compared to the OLT group, the grafts subjected to Post C algorithm(without significant prolonging the total ischemic time) especially with short stimulus and more cycles(10 s × 6) showed significant alleviation of morphological damage and graft function. Besides, the production of reactive oxidative agents(MDA) and neutrophil infiltration(MPO) were significantly depressed by Post C algorithm. Most of ERS related genes were down-regulated by Post C(10 s × 6), especially ATF4, Casp12, hspa4, ATF6 and ELF2, while p-Akt was up-regulated.Conclusions: Post C algorithm, especially 10 s × 6 algorithm, showed to be effective against rat liver graft IRI. These protective effects may be associated with its antioxidant, inhibition of ERS and activation of p-Akt expression of reperfusion injury salvage kinase pathway.

Effects of hole-injection through side-walls of large V-pits on efficiency droop in Ⅲ–nitride LEDs

Although the solid-state lighting market is growing rapidly, it is still difficult to obtain ultra-high brightness white light emitting diodes(LEDs). V-pits are inevitably introduced during the metalorganic chemical vapor deposition(MOCVD)growth of multiple quantum wells(MQWs) in Ⅲ–nitride LEDs, and thus affecting the carrier dynamics of the LEDs.Specifically designed structures are fabricated to study the influence of the V-pits on the hole transportation and efficiency droop, and double quantum wells(QWs) are used to monitor the transportation and distribution of holes based on their emission intensity. It is found that when compared with the planar QWs, the injection of holes into the QWs through the side walls of the V-pits changes the distribution of holes among the MQWs. This results in a higher probability of hole injection into the middle QWs and enhanced emission therein, and, consequently, a lower efficiency droop.