703 Koch’s triangle voltage mapping for cryoablation of slow pathway in children: preliminary data of a novel high density technique

Aims Different authors have described three-dimensional (3D) voltage mapping of the Koch’s triangle (KT) in order to find low-voltage bridges (LVBs) as targets for a successful transcatheter ablation (TCA) of the slow pathway (SP) in children. Recently, the advisor high density (HD) Grid™ mapping catheter was introduced as new multipolar catheter for HD mapping. The aim of the study was to describe our preliminary experience with the use of HD Grid™ catheter in LVB and electrophysiologically guided cryoablation of SP in children. Methods and results Twenty-one children (mean age 13 ± 3 years) with atrioventricular nodal re-entrant tachycardia (AVNRT) underwent cryoablation of SP guided by voltage HD mapping of the KT using HD Grid™ catheter. In order to better highlight the differences with conventional mapping, point collection was performed in each patient with this new multipolar catheter and with a quadripolar catheter. The conventional mapping collected 871 ± 262 points and used 211 ± 80 points in 887 ± 275 s, whereas HD mapping collected 7468 ± 2947 points, using 604 ± 165 points in 513 ± 181 s (P < 0.001). Moreover, the LVB area mapped with HD Grid™ was about one-half smaller and clearly delineated. Cryoablation acute success rate was 100%. Overall median fluoroscopy exposure was 0.08 (0.01–5.42) µGy/m2, with a median fluoroscopy time of 0.1 (0.0–0.6) min. During the follow-up (4.8 ± 3.7 months), there were no recurrences. No complications occurred. Conclusions Our preliminary experience shows that HD mapping is faster and offers higher spatial resolution and definition. Procedural time can be reduced maintaining the TCA safe, with reduced fluoroscopy use, and successful.

Characterization of conduction gaps at the pulmonary vein antra by omnipolar voltage mapping

Funding Acknowledgements Type of funding sources: Private grant(s) and/or Sponsorship. Main funding source(s): Abbott provided some software to perform special maps Introduction Voltage mapping of atrial tissue may be influenced by the direction of the activation front. Omnipolar electrograms may result in better characterization of the atrial tissue. However, little is known about characterization of the pulmonary vein (PV) antra with omnipolar mapping in patients with recurrent atrial fibrillation (AF) following PV isolation (PVI). Purpose To study differences in voltage between regions with (Gap) and without (No-Gap) conduction recurrence at the PV antra by both omnipolar and conventional bipolar mapping in redo PVI procedures. Methods Single centre prospective study of consecutive patients who underwent a redo PVI procedure for AF ablation. Activation and voltage bipolar maps were developed on a electroanatomical system (Ensite Precision) by a steerable catheter with a 16 grid-patterned electrode configuration (HD-Grid) during coronary sinus pacing at both 500 and 300 ms. Precise location of conduction gaps in the PV antra was attempted by atrial and PV pacing. Only conduction gaps that were ablated by ≤3 focal radiofrequency applications were included in the analysis. Electrograms recorded within 1 cm at both sides of the RF application site were considered related to the gap region. Off-line omnipolar voltage maps were developed with a dedicated experimental software after the procedure . Results 11 patients were included in the study and 18 gaps were found in 9 patients. 6762 (2688 Gap and 4074 No-Gap) electrograms were analyzed. Compared with No-Gap PV regions, Gap regions showed significantly (P < 0.0001) higher voltages by omnipolar mapping (0.3 ± 0.6 mV vs 1.1 ± 1.4 mV) and by absolute (0.2 ± 0.5 mV vs 0.8 ± 1.2 mV), grid-along (0.3 ± 0.5 mV vs 0.8 ± 1.2 mV) and grid-across (0.3 ± 0.5 mV vs 0.8 ± 1.1 mV) bipolar mapping. Omnipolar mapping resulted in higher voltage electrograms when compared with absolute bipole, longitudinal and horizontal bipolar electrograms (P < 0.0001). ROC curves (figure) to differentiate between Gap and No-Gap regions were slightly better for omnipolar electrograms (AUC 0.79) than for conventional grid -along or grid-across bipolar mapping (AUC 0.76 and 0.77) with the best discrimination value of 0.3 and 0.2 mV respectively. Conclusion: There are significant differences in voltage between conduction Gap and No-Gap regions at the PV antra which are more apparent with omnipolar than with conventional bipolar mapping. 0.3 mV and 0.2 mV values are the best to differentiate between PV conduction Gap and No-Gap regions with ominpolar and conventional mapping respectively

A sinusoidal transform of the visual field in cortical area V2

The retinotopic maps of many visual cortical areas are thought to follow the fundamental principles that have been described for primary visual cortex (V1) where nearby points on the retina map to nearby points on the surface of V1, and orthogonal axes of the retinal surface are represented along orthogonal axes of the cortical surface. Here we demonstrate a striking departure from this conventional mapping in the secondary visual area (V2) of the tree shrew. Although local retinotopy is preserved, orthogonal axes of the retina are represented along the same axis of the cortical surface, an unexpected geometry explained by an orderly sinusoidal transform of the retinal surface. This sinusoidal topography is ideally suited for achieving uniform coverage in an elongated area like V2, is predicted by mathematical models designed to achieve wiring minimization, and provides a novel explanation for stripe-like patterns of intra-cortical connections and stimulus response properties in V2. Our findings suggest that cortical circuits flexibly implement solutions to sensory surface representation, with dramatic consequences for the large-scale layout of topographic maps.

NGS Screening for Identification of Novel Pexophagy-Related Mutation in Arabidopsis thaliana

Peroxisomes are the type of organelles in eukaryotic cells that are involved in different biochemical pathways depending on the type of cell. We have isolated a number of peroxisome unusual positioning (peup) mutants, which display the accumulation of abnormal peroxisomes, and demonstrated that autophagy is involved in removing damaged organelles. These peup mutants also show defects of other autophagy-related processes, such as the recovery from dark-senescence, and also failed to induce vacuole-related vesicle formations during microautophagy under nutrient deprivations. The aim of this study was to identify the causative gene of the peup33 mutant using next-generation sequencing (NGS) as a tool. Identification of mutations with NGS will allow us to save time compared to the conventional mapping method. Here, we present the workflow of the experiment, the procedure of bioinformatic analysis and the software applied to the sequence data produced by NGS.

Analysis of Successive Land-Use Changes in Old Residential Area of “Festival of Art & Culture (FESTAC) Town” Lagos, Nigeria

In recent times, land use for commercial, residential, and transportation purposes among others is dislodging former units and bare sites as a result of structural alteration, mostly in the urban centers of Nigeria. The changes are due to various guises and structural shift, outright demolition and redevelopment and their impact is consequential. This paper assesses the current pattern which residential zones have assumed within the old Festival of Art and Culture (FESTAC) Town in Lagos, Nigeria. The methods used in the study included the delineation of the study area into six avenues which the researcher(s) adopted for the purpose of even coverage, as well as the use of structural questionnaires, base map and GPS in sourcing for necessary data on the field. Additionally, the data collected were assembled, coded and analyzed using simple descriptive statistics and conventional mapping techniques. The findings revealed the factors responsible for the alteration of land use to enhance financial gains, such as changing neighborhood characteristics and the evasion of permission from the town planning authorities. The findings also provided evidence that many structures still remain vulnerable to conversion, alteration, and/or demolition. The paper recommends that adequate permission should be granted by the legal authority before the conversion and rebuilding of any structure into a new land use.

Micro-reentry right atrial tachycardia originating from fossa ovalis: a case report of high-density mapping by PentaRay catheter

Background Micro-reentry tachycardia usually emerges in scar tissues related to post-atrial fibrillation ablation and cardiomyopathy. It is difficult to identify the micro-reentry circuit accurately by conventional mapping method. Case summary A 74-year-old man presented with paroxysmal atrial tachycardia (AT) presenting as palpitations. He was evaluated by an electrophysiological examination using a high-density CARTO mapping system. The mapping results showed the AT with a cycle length of 184 ms was focused on his right atrial fossa ovalis (FO). In this small area, the high-density mapping demonstrated a significant micro-reentrant tachycardia. Radiofrequency ablation at the centre of the micro-reentrant circuit successfully terminated the AT. No recurrences were observed during a 12-month follow-up. Discussion This case demonstrated a micro-reentrant AT originates from the FO without cardiomyopathy or previous ablation with specific loops. This is an unusual location for AT though and can cause difficulty for operators if it terminates or is non-sustained. High-density mapping using a PentaRay catheter can effectively characterize micro-reentrant circuits and determine the real target for ablation therapy.

WikiMedMap: Expanding the Phenotyping Mapping Toolbox Using Wikipedia

Researchers utilizing phenotypic data from diverse sources require matching of phenotypes to standard clinical vocabularies. Mapping phenotypes to vocabulary can be difficult, as existing tools are often incomplete, can be difficult to access, and can be cumbersome to use, especially for non-experts. We created WikiMedMap as a simple tool that leverages Wikipedia and maps phenotype strings to standard clinical vocabularies. We assessed WikiMedMap by mapping phenotype strings from questionnaires in the UK Biobank and from Mendelian diseases in Online Mendelian Inheritance in Man (OMIM) database to eight vocabularies: International Classification of Diseases, Ninth Revision (ICD-9), ICD-10, ICD-O, Medical Subject Headings (MeSH), OMIM, Disease Database, and MedlinePlus. WikiMedMap outperformed conventional mapping tools in finding potential matches for phenotype strings. We envision WikiMedMap as a technique that complements existing and established tools to map strings to clinical vocabularies that usually do not coexist in one source.

Influenza Classification from Short Reads with VAPOR Facilitates Robust Mapping Pipelines and Zoonotic Strain Detection for Routine Surveillance Applications

BackgroundInfluenza viruses are associated with a significant global public health burden. The segmented RNA genome of influenza changes continually due to mutation, and the accumulation of these changes within the antigenic recognition sites of haemagglutinin (HA) and neuraminidase (NA) in turn leads to annual epidemics. Influenza A is also zoonotic, allowing for exchange of segments between human and non-human viruses, resulting in new strains with pandemic potential. These processes necessitate a global surveillance system for influenza monitoring. To this end, whole-genome sequencing (WGS) has begun to emerge as a useful tool. However, due to the diversity and mutability of the influenza genome, and noise in short-read data, bioinformatics processing can present challenges.ResultsConventional mapping approaches can be insufficient when a sub-optimal reference strain is chosen. For short-read datasets simulated from influenza H1N1 HA sequences, read recovery after single-reference mapping was routinely as low as 90% for human-origin influenza sequences, and often lower than 10% for those from avian hosts. To this end, we developed a de Bruijn Graph (DBG)-based classifier of influenza WGS datasets: VAPOR. In real data benchmarking using 257 WGS read sets with corresponding de novo assemblies, VAPOR provided classifications for all samples with a mean of >99.8% identity to assembled contigs. This resulted in an increase in the number of mapped reads by 6.8% on average, up to a maximum of 13.3%. Additionally, using simulations, we demonstrate that classification from reads may be applied to detection of reassorted strains.ConclusionsVAPOR has potential to simplify bioinformatics pipelines for surveillance, providing a novel method for detection of influenza strains of human and non-human origin directly from reads, minimization of potential data loss and bias associated with conventional mapping, and allowing visualization of alignments that would otherwise require slow de novo assembly. Whilst with expertise and time these pitfalls can largely be avoided, with pre-classification they are remedied in a single step. Furthermore, our algorithm could be adapted in future to surveillance of other RNA viruses. VAPOR is available at https://github.com/connor-lab/vapor.