Transaortic septal myectomy at the time of aortic valve replacement for severe aortic stenosis: a case series of 55 cases.

Introduction: Symptomatic aortic valve stenosis (AS) is associated with asymmetric basal septal hypertrophy (ABSH) in 10% of cases. In this cohort, it has been suggested that rectification of the left ventricular outflow tract obstruction (LVOTO) by concomitant septal myectomy (CSM) can improve the results of aortic valve replacement (AVR). Objective: This study aims to present the technique of AVR with CSM for severe AS with ABSH and to determine the associated early and late post-operative outcomes. Methods: Fifty-five patients were prospectively recruited to undergo AVR with CSM between 2011 and 2021 at two centres. The primary outcomes were mortality within 30 days, incidence of post-operative ventricular septal defects (VSD) and prosthetic valve sizing. The secondary outcomes were in-hospital complications, permanent pacemaker implantation (PPI), survival at 15 months and changes on transthoracic echocardiogram. Results: Post-operative mortality was 1.8% and this figure was unchanged at 15-month follow-up. No patients developed a post-operative VSD. Intra-operatively, it was found that in 94.6% cases the direct valve sizing increased by one, when compared to the measurement made before CSM. The indexed effective orifice area (iEOA) was > 85 cm2/m2 in 96.4% and no patients had an iEOA ≤ 0.75 cm2/m2. Four patients (7.3%) required PPI due to complete atrioventricular block. Conclusion: AVR with CSM is a simple technique that can be utilised in severe AS with ABSH. There does not appear to be an increase in mortality or incidence of iatrogenic VSDs. Importantly, CSM allows for the implantation of a larger aortic valve compared to measurements made before CSM.

Prostacyclin mimetics inhibit DRP1-mediated pro-proliferative mitochondrial fragmentation in pulmonary arterial hypertension.

Pulmonary arterial hypertension (PAH) is a rare cardiopulmonary disorder, involving the remodelling of the small pulmonary arteries. Underlying this remodelling is the hyper-proliferation of pulmonary arterial smooth muscle cells within the medial layers of these arteries and their encroachment on the lumen. Previous studies have demonstrated an association between excessive mitochondrial fragmentation, a consequence of increased expression and post-translational activation of the mitochondrial fission protein dynamin-related protein 1 (DRP1), and pathological proliferation in PASMCs derived from PAH patients. However, the impact of prostacyclin mimetics, widely used in the treatment of PAH, on this pathological mitochondrial fragmentation remains unexplored. We hypothesise that these agents, which are known to attenuate the proliferative phenotype of PAH PASMCs, do so in part by inhibiting mitochondrial fragmentation. In this study, we confirmed the previously reported increase in DRP1-mediated mitochondrial hyper-fragmentation in PAH PASMCs. We then showed that the prostacyclin mimetic treprostinil signals via either the Gs-coupled IP or EP2 receptor to inhibit mitochondrial fragmentation and the associated hyper-proliferation in a manner analogous to the DRP1 inhibitor Mdivi-1. We also showed that treprostinil recruits either the IP or EP2 receptor to activate PKA and induce the phosphorylation of DRP1 at the inhibitory residue S637 and inhibit that at the stimulatory residue S616, both of which are suggestive of reduced DRP1 fission activity. Like treprostinil, MRE-269, an IP receptor agonist, and butaprost, an EP2 receptor agonist, attenuated DRP1-mediated mitochondrial fragmentation through PKA. We conclude that prostacyclin mimetics produce their anti-proliferative effects on PAH PASMCs in part by inhibiting DRP1-mediated mitochondrial fragmentation.

Cor triatriatum dexter as an incidental finding due to symptomatic bicuspid aortic valve stenosis.

Cor triatriatum is a rare congenital heart defect in which a thin, fibro-muscular membrane divides the left or right atrium into two chambers resulting in a triatrial heart. Subdivision of the left atrium named cor triatriatum sinister (CTS), is the more common form, whereas the right atrial equivalent called cor triatriatum dexter (CTD) is rarer. They account for up to 0.4% and 0.025% of the burden of congenital heart disease respectively. We present the case of CTD found incidentally with transthoracic echocardiography for a patient who underwent aortic valve replacement for symptomatic bicuspid aortic valve stenosis.

Therapeutic potential of inhibiting histone 3 lysine 27 demethylases: a review of the literature.

Histone 3 lysine 27 (H3K27) demethylation constitutes an important epigenetic mechanism of gene activation. It is mediated by the Jumonji C domain-containing lysine demethylases KDM6A and KDM6B, both of which have been implicated in a wide myriad of diseases, including blood and solid tumours, autoimmune and inflammatory disorders, and infectious diseases. Here, we review and summarise the pre-clinical evidence, both in vitro and in vivo, in support of the therapeutic potential of inhibiting H3K27-targeting demethylases, with a focus on the small-molecule inhibitor GSK-J4. In malignancies, KDM6A/B inhibition possesses the ability to inhibit proliferation, induce apoptosis, promote differentiation, and heighten sensitivity to currently employed chemotherapeutics. KDM6A/B inhibition also comprises a potent anti-inflammatory approach in inflammatory and autoimmune disorders associated with inappropriately exuberant inflammatory and autoimmune responses, restoring immunological homeostasis to inflamed tissues. With respect to infectious diseases, KDM6A/B inhibition can suppress the growth of infectious pathogens and attenuate the immunopathology precipitated by these pathogens. The pre-clinical in vitro and in vivo data, summarised in this review, suggest that inhibiting H3K27 demethylases holds immense therapeutic potential in many diseases.