Search

IntroductionPacing-induced cardiomyopathy occasionally occurs in patients undergoing pacemaker implantation. Although compared with right ventricular (RV) apical pacing, RV septal pacing can attenuate left ventricular dyssynchrony; the success rate of lead placement on the RV septum using the stylet system is low. Additionally, no randomised controlled trial has addressed the issue regarding the accuracy of RV lead placement on the RV septum using the stylet and delivery catheter systems. This study hypothesises that a newly available delivery catheter system can improve the accuracy of RV lead placement on the RV septum.Methods and analysisIn a multicentre, prospective, randomised, single-blind, controlled trial, 70 patients with pacemaker indication owing to atrioventricular block will be randomised to either the delivery catheter or stylet group before the pacemaker implantation procedure. The position of the RV lead tip will be assessed using ECG-gated cardiac CT in all patients within 4 weeks after pacemaker implantation. Lead tip positions are classified into three groups: (1) RV septum, (2) anterior/posterior edge of the RV septal wall and (3) RV free wall. The primary endpoint will be the success rate of RV lead tip placement on the RV septum, which will be evaluated using cardiac CT.Ethics and disseminationThis study will be conducted according to the stipulations of the Helsinki Declaration and the institutional review board of Hamamatsu University School of Medicine. The results of the study will be disseminated at several research conferences and will be published in peer-reviewed journals.Trial registration numberjRCTs042200014; Pre-results.

Factor Xa (FXa) inhibitors are recommended for use in fixed doses without laboratory monitoring. However, prior studies reported the importance of establishing biomarkers representing anticoagulation intensity related to bleeding or thrombotic events. To test the hypothesis that prothrombin activation fragment 1 and 2 (F1 + 2), a non-specific marker of thrombin generation, could be altered during FXa inhibitor treatment in patients with atrial fibrillation. We conducted the study in two different clinical settings. First, the interrelations among biomarkers representing coagulation/fibrinolysis were investigated in 80 patients in an outpatient clinic. Second, these biomarkers were evaluated in 75 patients who underwent radiofrequency catheter ablation. Plasma concentration of FXa inhibitors was evaluated using an anti-FXa chromogenic assay (C-Xa). In the outpatient study, only F1 + 2 exhibited a significant and negative association with C-Xa (rS = − 0.315, p = 0.026), and 37% of the variance could be explained by C-Xa levels. F1 + 2 levels above the reference range (> 229 pmol/L) could be considered as a cut-off to identify poor patient compliance or under-dosing. In the peri-ablation study, increased F1 + 2 levels were associated with decline of C-Xa levels after periprocedural discontinuation of FXa inhibitors, which was greater in the rivaroxaban group than in the apixaban group. F1 + 2 showed modest and inverse association with plasma concentration of rivaroxaban and apixaban in patients with atrial fibrillation. Larger study to test the hypothesis that continued thrombin generation despite anticoagulation is associated with a heightened risk of clinical events is required.

Coronary sinus ostial atresia is rare and usually not clinically relevant, but it should be noted in cases of cardiac resynchronization therapy. A rare case of successful left ventricular lead implantation for cardiac resynchronization therapy via the left superior vena cava in a patient with coronary sinus ostial atresia is reported. The persistent left superior vena cava associated with these cases tends to be smaller than usual in its diameter and difficult to identify, since the direction of venous drainage is reversed. Therefore, in the present case, it was useful to use a small-diameter, soft inner catheter as a guiding catheter to perform selective imaging and avoid vascular injury. In addition, it appeared to be important to plan the surgical strategy using prior imaging information, since it would be difficult to obtain the backup needed for lead insertion. 〈 Learning objective: Cardiac resynchronization therapy via the left superior vena cava with coronary sinus ostial atresia is generally possible without problems if prior imaging information is available, such as three-dimensional computed tomography and the venous phase of coronary angiography. It is important to determine whether there is a persistent left superior vena cava before the procedure. Thromboprophylaxis remains controversial in this situation.〉

Recently, gut-dwelling bifidobacteria from chimpanzees, which are phylogenetically close to humans and have feeding habits similar to humans, have been frequently investigated. Given this, we speculated that like humans, chimpanzees would have a unique diversity of bifidobacteria. We herein describe a taxonomically novel member of bifidobacteria isolated from fecal samples of captive chimpanzees. Bifidobacteria were detected in all fecal samples by quantitative polymerase chain reaction. A Bifidobacterium pseudolongum-like species, which could not be detected using B. pseudolongum-specific primers targeting the groEL gene sequence, was dominant in the feces of five chimpanzees. Seven bifidobacterial strains were isolated from this group of five chimpanzees, and all isolates were identified as B. pseudolongum. B. pseudolongum has previously often been isolated from non-primate animals as well as humans; however, here we demonstrate its presence in a nonhuman primate species.

Atrial fibrillation (AF) is the most common cardiac arrhythmia, but its proarrhythmic mechanism remains to be elucidated. Glutamate (Glu) and taurine (Tau) are present in the myocardium at substantially higher concentrations than in the plasma, suggesting their active role in myocardium. Here, we tested the hypothesis that the metabolism of Glu and Tau is altered in association with the generation of reactive oxygen species (ROS) in patients with AF. Fifty patients with paroxysmal AF and 50 control subjects without a history of AF were consecutively enrolled. Circulating Glu and Tau levels were measured and correlations between Glu/Tau and ROS levels were examined. Glu/Tau content was significantly higher in patients with AF versus controls (Glu:79.2±23.9versus60.5±25.2 nmol/L; Tau:78.8±19.8versus68.5±20.8 nmol/L; mean ± standard deviation (SD),p<0.001for both). Glu/Tau levels also showed an independent association with AF by multiple logistic regression analysis. Glu and Tau levels both showed significant positive associations with plasma hydroperoxide concentrations. These data suggest a novel pathophysiological role of Glu and Tau in association with ROS production in paroxysmal AF, providing new insights into the elevated amino acid content in cardiac disease.