Comprehensive assessment of Mahaim accessory pathways’ anatomic distribution

Objective To present the authors’ experience of Mahaim-type accessory pathways (MAPs), focusing on anatomic localizations. Methods Data from consecutive patients who underwent electrophysiological study (EPS) for MAP ablation in two tertiary centres, between January 1998 and June 2020, were retrospectively analysed. Results Of the 55 included patients, 27 (49.1%) were male, and the overall mean age was 29.5 ± 11.6 years (range, 12–66 years). MAPs were ablated at the tricuspid annulus in 43 patients (78.2%), mitral annulus in four patients (7.3%), paraseptal region in three patients (5.5%), and right ventricle mid-apical region in five patients (9.1%). Among 49 patients who planned for ablation therapy, the success rate was 91.8% (45 patients). Conclusion MAPs were most often ablated at the lateral aspect of the tricuspid annuli, sometimes at other sides of the tricuspid and mitral annuli, and infrequently in the right ventricle. The M potential mapping technique is likely to be a useful target for ablation of MAPs.

Epicardial and Endocardial Ablation Based on Channel Mapping in Patients With Ventricular Tachycardia and Chronic Chagasic Cardiomyopathy: Importance of Late Potential Mapping During Sinus Rhythm to Recognize the Critical Substrate

Background Ventricular tachycardia (VT) in patients with chronic chagasic cardiomyopathy (CCC) is associated with considerable morbidity and mortality. Catheter ablation of VT in patients with CCC is very complex and challenging. The main goal of this work was to assess the efficacy of VT catheter ablation guided by late potentials (LPs) in patients with CCC. Methods and Results Seventeen consecutive patients with refractory VT and CCC were prospectively included in the study. Combined endo‐epicardial voltage and late activation mapping were obtained during baseline rhythm to define scarred and LP areas, respectively. The end point of the ablation procedure was the elimination of all identified LPs. Epicardial and endocardial dense scars (<0.5 mV) were detected in 17/17 and 15/17 patients, respectively. LPs were detected in the epicardial scars of 16/17 patients and in the endocardial scars of 14/15 patients. A total of 63 VTs were induced in 17 patients; 22/63 (33%) were stable and entrained, presenting LPs recorded in the isthmus sites. The end point of ablation was achieved in 15 of 17 patients. Ablation was not completed in 2 patients because of cardiac tamponade or vicinity of the phrenic nerve and circumflex artery. Three patients (2 with unsuccessful ablation) had VT recurrence during follow‐up (39 months). Conclusions Endo‐epicardial LP mapping allows us to identify the putative isthmuses of different VTs and effectively perform catheter ablation in patients with CCC and drug‐refractory VTs.

General 1-D hydrogeological model for temporal near-surface loess saturation assessment for the needs of radon potential mapping

Radon gas has high mobility and is driven by advection and diffusion with the soil gas throughout connected and water-unsaturated pores and/or cracks in permeable rocks and soils. Hence the radon potential of the area could be dependent on not only geology as a constant source of radon but also from the changes of the saturation state of the ground. The loess complex, characterized by its permeability and usual state of unsaturation, covers 10% of the Bulgarian territory. The study deals with the principles of unsaturated domain modeling. An attempt of generic vertical infiltration model coinciding with the most upper part of loess vadose zone was performed.

Probing the charge injection and dissipation in graphene oxide–epoxy composite

The inorganic filler can modify the electrical and dielectric properties of polymeric composites. However, it is challenging to understand the local charge injection and dissipation in composites through traditional characterization at nanoscale. In this work, we provide a potential mapping of the charge injection and dissipation in the local area of graphene oxide/epoxy resin (GO/EP) composite under various biases by Kelvin probe force microscopy (KPFM) with high spatial resolution. Thus, an improved KPFM experimental setup is used to inject charges at the fixed point to demonstrate surface charge dissipation around the interface between GO and EP. It is found that the charge is more easily injected into the GO/EP nanocomposites and dissipates more quickly in nanocomposite than in neat epoxy resins. Meanwhile, the electrons diffuse more rapidly than holes in pure EP and nanocomposites. The faster charge injection and dissipation of GO/EP composite are ascribed to the filler of GO which has much higher conductivity than that of neat epoxy. This work offers significant insights into the understanding of charge injection and dissipation in dielectric composites.