Inter-tag Distance Research Articles

Dual energy for pulmonary vein isolation using dual-energy focal ablation technology integrated with a three-dimensional mapping system: SmartfIRE 3-month results.

Contact force (CF)-sensing radiofrequency (RF) catheters with an ablation index have shown reproducible outcomes for the treatment of atrial fibrillation (AF) in large multicentre studies. A dual-energy (DE) focal CF catheter to deliver RF and unipolar/biphasic pulsed field ablation (PFA), integrated with a three-dimensional (3D) mapping system, can provide operators with additional flexibility. The SmartfIRE study assessed the safety and efficacy of this novel technology for the treatment of drug-refractory, symptomatic paroxysmal AF. Results at 3 months post-ablation are presented here. Pulmonary vein isolation (PVI) was performed using a DE focal, irrigated CF-sensing catheter with the recommendation of PFA at posterior/inferior and RF ablation at the anterior/ridge/carina segments. Irrespective of energy, a tag size of 3 mm; an inter-tag distance ≤6 mm; a target index of 550 for anterior, roof, ridge, and carina; and a target index of 400 for posterior and inferior were recommended. Cavotricuspid isthmus ablation was permitted in patients with documented typical atrial flutter. The primary effectiveness endpoint was acute procedural success. The primary safety endpoint was the rate of primary adverse events (PAEs) within 7 days of the procedure. A prespecified patient subset underwent oesophageal endoscopy (EE; 72 h post-procedure), neurological assessment (NA; pre-procedure and discharge), and cardiac computed tomography (CT)/magnetic resonance angiogram (MRA) imaging (pre-procedure and 3 months post-procedure) for additional safety evaluation, and a mandatory remapping procedure (Day 75 ± 15) for PVI durability assessment. Of 149 patients enrolled between February and June 2023, 140 had the study catheter inserted (safety analysis set) and 137 had ablation energy delivered (per-protocol analysis set). The median (Q1/Q3) total procedure and fluoroscopy times were 108.0 (91.0/126.0) and 4.2 (2.3/7.7) min (n = 137). The acute procedural success rate was 100%. First-pass isolation was achieved in 89.1% of patients and 96.8% of veins. Cavotricuspid isthmus ablations were successfully performed in 12 patients [pulsed field (PF) only: 6, RF only: 5, and RF/PF: 1]. The PAE rate was 4.4% [6/137 patients; 2 pulmonary vein (PV) stenoses, 2 cardiac tamponades/perforations, 1 stroke, and 1 pericarditis]. No coronary artery spasm was reported. No oesophageal lesion was seen in the EE subset (0/31, 0%). In the NA subset (n = 30), microemboli lesions were identified in 2 patients (2/30, 6.7%), both of which were resolved at follow-up; only 1 was symptomatic (silent cerebral lesion, 3.3%). In the CT/MRA subset (n = 30), severe PV narrowing (of >70%) was detected in 2 patients (2/30, 6.7%; vein level 2/128, 1.6%), of whom 1 underwent dilatation and stenting and 1 was asymptomatic; both were associated with high index values and a small inter-tag distance. In the PV durability subset (n = 30), 100/115 treated PVs (87%) were durably isolated and 18/30 patients (60.0%) had all PVs durably isolated. A DE focal CF catheter with 3D mapping integration showed a 100% acute success rate with an acceptable safety profile in the treatment of paroxysmal AF. Prespecified 3-month remapping showed notable PVI durability. ClinicalTrials.gov Identifier: NCT05752487.

CLOSE-Guided Pulmonary Vein Isolation to Treat Persistent Atrial Fibrillation: 1-Year Outcome.

CLOSE-guided pulmonary vein isolation (PVI) is based on contiguous and optimized (Ablation Index-guided) radiofrequency lesions. The efficacy of CLOSE-guided PVI in persistent atrial fibrillation (AF) treatment has been poorly evaluated. In two centers, 50 patients eligible for persistent AF ablation underwent CLOSE-guided PVI (Ablation Index ≥ 450 at the anterior wall, ≥300 at posterior wall, intertag distance ≤ 6 mm). If PVI failed to restore sinus rhythm (SR), electrical cardioversion (ECV) was performed. Atrial substrate modification (ASM) was performed only if PVI and ECV failed to restore SR. Recurrence was defined as any recorded episode of AF, atrial tachycardia (AT) or atrial flutter (AFL) > 30 s on Holter electrocardiographs at 3, 6 and 12 months. From the 50 patients (64 ± 10 years, 14% long-standing persistent AF), SR was restored by ECV in 34 patients (68%) 56 ± 38 days prior to ablation. On the day of ablation, 42 patients (84%) were on class I-III anti-arrhythmic drug therapy (ADT) and the rhythm was AF in 23/50 patients. PVI was achieved in all patients; after PVI, ECV was required in 21 patients and ASM in 1 patient. The mean procedure time, radiofrequency time and fluoroscopy time were 141 ± 33 min, 23 ± 7 min and 7 ± 6 min, respectively. At 12 months, single-procedure freedom from AF/AT/AFL was 80%, with 19 patients (38%) receiving class I-III ADT. In a population of patients with persistent AF monitored with intermittent cardiac rhythm recordings, CLOSE-guided PVI resulted in high single-procedure arrhythmia-free survival at 1 year. Future large-scale studies involving continuous cardiac monitoring are necessary.

Visual-optical positioning and configuration of non-identified electronic pricing tags on retail shelves

Firstly, a new positioning methodology for electronic pricing tags (EPTs) is proposed, performed by a Visual-Optical Mobile Module (VOMM) on the shelf. The module is composed of a monocular mobile camera and an infrared laser emitter built into a precise X-Y-Z angle divider driven by subdivision control of a stepping motor for Simultaneous Localization and Mapping (SLAM). The inter-tag distance between two EPTs can be down to a minimum of 2 mm. Secondly, the batteryoperated EPT consists of an infrared receiver and a low-cost MCU with LC-display. All EPTs can be positioned and automatically assigned to a specific ID. Hence, neither Radio Frequency Identification (RFID) nor a beacon is needed to tag the products. All the off-the-shelf products can be freely placed anywhere on the shelves. Thirdly, all individual EPTs can be auto-configured by a VOMM via Line-of-Sight (LoS) communication. The initial database simply records product identification and description, regular price, promotion price and sale period. Finally, the rotatable VOMM is installed on the ceiling, and a 3D floor plan can be generated to show the coordinates of products and EPTs. Shelves and zones can be generated automatically by using visual recognition and the information from the database according to the position of all EPTs on the shelves.

How Close Are We toward an Optimal Balance in Safety and Efficacy in Catheter Ablation of Atrial Fibrillation? Lessons from the CLOSE Protocol.

Catheter ablation for atrial fibrillation (AF) is a common treatment strategy in patients with drug-resistant, symptomatic AF. In patients with paroxysmal and short-standing persistent AF, pulmonary vein isolation (PVI) is often enough to prevent recurrence of atrial tachyarrhythmia (ATA). Point-by-point encircling of the PVs with radiofrequency (RF) applications, together with cryoballoon ablation, have been the mainstay strategies for the last 10 to 20 years. Each of these strategies, however, suffers from the delicate balance between preventing PV reconnection, on the one hand (toward more energy), and preventing (mainly esophageal) complications (toward less energy), on the other. The CLOSE protocol was developed as an RF ablation strategy that would result in the safe creation of durable isolation leading to improved outcomes. Basically, the aim of the protocol is to enclose the pulmonary veins with stable, contiguous (intertag distance, ITD ≤ 6 mm) and optimized lesions (35 Watts, W, RF applications up to ablation index targets of ≥400 and ≥550 at the posterior and anterior wall). In this review, we describe the background of the CLOSE protocol and the studies from the St Jan Bruges research group on procedural performance, efficacy, and safety of the CLOSE protocol in (a) single-center prospective PILOT study (CLOSE-PILOT), (b) a single-center prospective study with continuous rhythm monitoring (CLOSE to CURE), (c) a database of systematic esophageal endoscopic studies, (d) a multicenter prospective study (VISTAX), and (e) the CLOSE database (comprising > 400 patients). We also discuss the results of the randomized POWER-AF study comparing conventional CLOSE to high power CLOSE (up to 50 W). Finally, we discuss the performance, safety, and efficacy of the CLOSE protocol in light of the emerging changes in the field of catheter ablation being ultra-short high-power ablation and electroporation.

Ablation Index-guided 50W ablation for left atrial posterior wall isolation compared with lower powers: feasibility and lesion level analysis

Abstract Funding Acknowledgements Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Groupe de Rythmologie de la Société Française de Rythmologie Background Posterior Wall Isolation (PWI) is increasingly performed for Atrial Fibrillation (AF). The use of Ablation Index (AI)-guided 50W ablation for PWI has not been described, nor the interplay between ablation parameters at this power when compared to lower powers. Methods 40 consecutive AF patients (26 males, 65.5 ± 10.0 years. 95% non-paroxysmal AF) underwent PWI following pulmonary vein isolation. A roof line and floor line were created with point-by-point ablation, targeting a contact force (CF) of 10-30g, AI 550-600 on the roof and 400-450 on the floor, and inter-tag distance of <6mm. 35-40W powers were used for the first 20 patients, and 50W used for the next 20. Generator impedance was monitored in real time for each lesion. Ablation inside the box was delivered in case of failure of first pass isolation (FPI). All VisiTags (n = 959) were analyzed retrospectively. Results PWI was successful in 19(95%) of the 35-40W group and in all 20 patients in the 50W group, with FPI seen in 8(40%) and 10(50%) respectively, p = 0.53. The mean CF and number of RF applications on the roof. floor and inside the box were similar between the two groups. Ablation time per lesion (10.4 [8.8-12.5]sec) and total ablation time per patient (3.84[3.34-4.66] min) were shorter in the 50W group as compared to 35-40W (13.0 [11.6-16.2] sec and 5.86 [4.23-7.73] min respectively), p < 0.005. The mean AI and Impedance Drop were larger in the 50W group (Table). There was no steam pop observed in any of the 959 radiofrequency applications. Conclusion Ablation Index guided 50W ablation has a very high success rate for posterior wall isolation with shorter ablation times and higher impedance drop compared to conventional powers. Steam pops may be avoidable by targeting CF < 30g, and by monitoring impedance in real-time. 50W Group(N = 458) 35-40W Group(N = 501) p-value Number of lesions (s, IQR)Roof lineFloor lineAdditional ablation inside box 21.5 [19.5-26.3]7.0 [5.8-9.0]13.0 [10.8-14.3]6.0 [6.0-6.8] 24.0 [20.8-29.5]8.0 [6.0-10.0]12.5 [10.8-14.0]5.5 [2.8-9.0] 0.330.180.850.59 Ablation Time per lesion (s, IQR)Roof lineFloor lineAdditional ablation inside box 10.4 [8.8-12.5]13.0 [10.9-16.0]9.9 [8.7-11.4]8.1 [6.9-9.0] 13.0 [11.6-16.2]14.5 [12.4-19.0]12.7 [11.4-15.9]11.8 [10.6-14.0] <0.005<0.005<0.005<0.005 Total RF Time (min, IQR)Roof lineFloor lineAdditional ablation inside box 3.84 [3.34-4.66]1.54 [1.15-1.90]2.06 [1.68-2.54]0.79 [0.65-1.07] 5.86 [4.23-7.73]1.98 [1.62-2.59]2.78 [2.28-3.25]1.07 [0.59-1.42] < 0.0050.0190.0090.50 Impedance Drop (ohms, IQR)Roof lineFloor lineAdditional ablation inside box 7.4 [5.2-10.3]8.7 [6.1-11.3]6.9 [5.0-10.1]7.1 [5.4-9.8] 6.9 [4.8-9.7]7.5 [5.1-10.0]6.0 [4.2-8.3]8.3 [5.8-10.9] 0.0070.04< 0.0050.17 Contact Force (g, IQR)Roof lineFloor lineAdditional ablation inside box 21.1 [14.5-30.3]23.9 [17.8-32.7]19.2 [13.2-25.3]25.5 [18.5-36.9] 21.2 [14.9-28.1]24.3 [17.2-30.3]19.0 [14.1-25.0]23.1 [16.9-31.7] 0.560.450.870.21 Ablation Index (IQR)Roof lineFloor lineAdditional ablation inside box 471 [441-519]560 [509-571]453 [436-475]461 [430-488] 461 [434-493]502 [466-541]446 [426-464]455 [434-478] < 0.005< 0.005< 0.0050.59 Lesion level analysis for Posterior Wall Isolation

Characterizing clinical outcomes and factors associated with conduction gaps in VISITAG SURPOINT-guided catheter ablation for atrial fibrillation.

PurposeAlthough usefulness of VISITAG SURPOINT (VS) on pulmonary vein isolation (PVI) in catheter ablation of atrial fibrillation has been reported, optimal VS thresholds can depend on the inter‐tag distance (ITD) and vice versa. We validated the efficacy of PVI with lower target ITDs and VS values than in previous studies.MethodsRetrospective review of consecutive patients (N = 100) with paroxysmal (n = 32) or persistent AF (n = 68) undergoing VS‐guided ablation between 09/2018 and 08/2019 was conducted. All procedures were performed by two operators. Target VS values were 425 (anterior), 375 (posterior), and 325 (near the esophagus). Target ITD was 4 mm.ResultsAcute PVI was achieved in all cases, however, 13 residual gaps in 12 patients were observed after initial encirclement (first pass isolation: 88%). Ten gaps due to spontaneous PV reconnections (PVR) were found in nine patients (9%). These 23 gaps had similar median VS (gap‐related vs non‐gap: 429 vs 410, P = .4545) and power (36 vs 36W, P = .4843), higher contact force (13.8 vs 11.0g, P = .0061), and larger ITD (5.3 vs 3.7mm, P < .001) when compared to the remaining tags. Only ITDs were independently associated with gap formation in multivariate analysis. One‐year Kaplan‐Meier freedom from any atrial arrhythmia was 87.2%. Eight patients received repeat ablation (8.1%) and of these, 6 (75%) were free from PVR.ConclusionFavorable rates of first pass isolation, acute PVR, and long‐term procedure success were achieved using lower VS values than in previous reports. With a target VS value of 375‐425, ITDs of 4 mm was sufficient for durable PVI.

Identification of deliberate catheter motion at the left atrial posterior wall during pulmonary vein isolation: Validity of respiratory motion adjustment.

During automated radiofrequency (RF) annotation-guided pulmonary vein isolation (PVI), respiratory motion adjustment (RMA) is recommended, yet lacks in vivo validation. Following contact force (CF) PVI (continuous RF, 30 W) using general anesthesia and automated RF annotation-guidance (VISITAG™: force-over-time 100% minimum 1 g; 2 mm position stability; ACCURESP™ RMA "off") in 25 patients, we retrospectively examined RMA settings "on" versus "off" at the left atrial posterior wall (LAPW). Respiratory motion detection occurred in eight, permitting offline retrospective comparison of RMA settings. Significant differences in LAPW RF auto-annotation occurred according to RMA setting, with curves displaying catheter position, CF and impedance data indicating "best-fit" for catheter motion detection using RMA "off."Comparing RMA "on" versus "off,"respectively: total annotated sites, 82 versus 98; median RF duration per-site, 13.3versus 10.6 s (p < 0.0001); median force time integral177versus 130 gs (p = 0.0002); mean inter-tag distance (ITD), 6.0versus 4.8 mm (p = 0.002). Considering LAPW annotated site 1-to-2 transitions resulting from deliberate catheter movement, 3 concurrent with inadvertent 0 g CF demonstrated < 0.6 s difference in RF duration. However, 13 deliberate catheter movements during constant tissue contact (ITD range: 2.1-7.0 mm) demonstrated (mean) site-1 RF duration difference 3.7 s (range: -1.3 to 11.3 s): considering multiple measures of catheter position instability, the appropriate indication of deliberate catheter motion occurred with RMA "off" in all. ACCURESP™ respiratory motion adjustment importantly delayed the identification of deliberate and clinically relevant catheter motion during LAPW RF delivery, rendering auto-annotated RF display invalid. Operators seeking greater accuracy during auto-annotated RF delivery should avoid RMA use.

Prospective Randomized Evaluation of High Power During CLOSE-Guided Pulmonary Vein Isolation: The POWER-AF Study.

CLOSE-guided atrial fibrillation (AF) ablation is based on contiguous (intertag distance ≤6 mm), optimized (Ablation Index >550 anteriorly and >400 posteriorly) point-by-point radiofrequency lesions. The optimal radiofrequency power remains unknown. The POWER-AF study is a prospective, randomized controlled monocentric study including patients with paroxysmal AF, planned for first CLOSE-guided pulmonary vein isolation using a contact force radiofrequency catheter (Thermocool SmartTouch, Biosense Webster, Inc, Irvine, CA). A total of 100 patients were randomized into 2 groups (1:1). The control group received AF ablation using the standard CLOSE protocol (35 W), whereas in the experimental group, pulmonary vein isolation was performed using high power (45 W). Endoscopic evaluation was performed in patients with intraesophageal temperature rise >38.5 °C. The resulting sample size was 96 (48+48) patients. In the high power group, shorter procedure time (80 versus 102 minutes, P<0.001), shorter total radiofrequency application time (16 versus 26 minutes, P<0.001), and radiofrequency time per application (26 versus 37 s anteriorly, P<0.001 and 13 versus 17 s posteriorly, P<0.001) were observed. Endoscopic evaluation (performed in 19/48 versus 25/48 patients respectively, P=0.31) showed an ulcerative perforation in a high power group patient (treated by endoscopic stenting and normalization after ≈4 months) and a superficial ulcerative lesion in a control group patient (conservative treatment). Both occurred following excessive Ablation Index applications (up to 460 and 480, respectively) with excessive contact force (30 g on average, with peaks up to 50 g). Six-months AF recurrence was not significantly different (10% in high power versus 8% in control, P=0.74). This randomized controlled study shows that a 45 W radiofrequency power CLOSE protocol in patients with paroxysmal AF significantly increases the global procedural efficiency with similar midterm efficacy. However, our study showed a narrower safety margin and a limited increased efficiency at the posterior wall using high power. This advocates against the use of high power in the region neighboring the esophagus.

An Assistive Technology Solution for User Activity Monitoring Exploiting Passive RFID.

Population ageing is having a direct influence on serious health issues, including hampered mobility and physical decline. Good habits in performing physical activities, in addition to eating and drinking, are essential to improve the life quality of the elderly population. Technological solutions, aiming at increasing awareness or providing reminders to eat/drink regularly, can have a significant impact in this scenario. These solutions enable the possibility to constantly monitor deviations from users’ normal behavior, thus allowing reminders to be provided to users/caregivers. In this context, this paper presents a radio-frequency identification (RFID) system to monitor user’s habits, such as the use of food, beverages, and/or drugs. The device was optimized to fulfill specifications imposed by the addressed application. The approach could be extended for the monitoring of home appliances, environment exploitation, and activity rate. Advantages of the approach compared to other solutions, e.g., based on cameras, are related to the low level of invasiveness and flexibility of the adopted technology. A major contribution of this paper is related to the wide investigation of system behavior, which is aimed to define the optimal working conditions of the system, with regards to the power budget, user (antenna)-tag reading range, and the optimal inter-tag distance. To investigate the performance of the system in tag detection, experiments were performed in a scenario replicating a home environment. To achieve this aim, specificity and sensitivity indexes were computed to provide an objective evaluation of the system performance. For the case considered, if proper conditions are meet, a specificity value of 0.9 and a sensitivity value of 1 were estimated.

1242The flexibility, ease of using, and leaving curve of a standardized ablation index workflow for catheter ablation of paroxysmal atrial fibrillation

Abstract Background/Introduction The ‘CLOSE’ protocol, incorporating standardized ablation index (AI) targets in conjunction with defined inter-tag distance (ITD) has been shown to improve the acute and long-term success of pulmonary vein isolation (PVI) when treating paroxysmal atrial fibrillation (PAF). The reproducibility and learning curve for this protocol has not been studied. Purpose To assess the acute and long-term efficacy of CLOSE PVI across multiple operators (n = 37) in the 17-centre European study ‘VISTAX’. Methods 329 patients with PAF (61.8% male, 61.3 ± 10.1 years) underwent PVI according to the CLOSE protocol, with target AI values for each lesion of ≥400 on the posterior wall and ≥550 on the anterior wall, and target ITD of ≤6mm. Each 3-dimensional electroanatomic map was evaluated at a core lab where adherence to each of these criteria was assessed. 281/329 patients (85.1%) fulfilled all standardized workflow requirements and were adjudicated as having their PVI per-protocol (PP). First pass PVI and acute effectiveness (adenosine-proof first pass PVI at 30-minute challenge) were recorded. Clinical effectiveness was assessed as freedom from atrial arrhythmia recurrence through 12 months recorded via transtelephonic monitoring (weekly and symptomatically), in addition to holter and electrocardiogram monitoring during 3,6,12 month follow up visits. Learning curve analysis was evaluated on all investigators. Results First pass PVI rates were similar in the overall (86%) and PP cohorts (85%), as was acute effectiveness (82% in both cohorts). Freedom from atrial arrhythmia at 12 months too was identical for both cohorts (79%). Total procedure time and total ablation time decreased by an average 8 minutes and 10 minutes respectively after the first procedure and then showed further steady decreases over the number of ablations performed by the investigator (Figure). The procedural efficiencies and clinical success were reproducible across different centers. No significant deviations were found from individual sites. Conclusion The standardized CLOSE workflow is reproducible across centres, and is ‘forgiving’ without impacting on high efficacy of almost 80%. The learning curve is short, suggesting that the excellent clinical results can be replicated widely and easily. Abstract Figure. Learning Curves- Procedure &amp; Ablation

P956Improved quality of life and symptomatic atrial fibrillation reduction in patients treated with a standardized ablation index workflow

Abstract Background/Introduction The use of a standardized ‘CLOSE’ ablation workflow for pulmonary vein isolation (PVI), with defined inter-tag distance (ITD) with targeted ablation index (AI) values, has been shown in single centre reports to result in good outcomes. The effect of this approach on patients’ quality of life (QoL) has not been studied. Purpose To evaluate the effects of paroxysmal atrial fibrillation (PAF) ablation by the CLOSE workflow on QoL and symptomatic AF reduction in the multicenter VISTAX study. Methods 329 patients with PAF (61.5% male, 61.3 ± 10.1 year) were treated at 17 European centres by point-by-point radiofrequency ablation using the CLOSE protocol to achieve PVI. An ITD ≤6mm and AI values of ≥400 on the posterior wall and ≥550 on the anterior wall were targeted. The AI value on the posterior wall was lowered as per investigator discretion in case of safety concerns. Patients were monitored for atrial arrhythmia recurrences via weekly and symptom-activated transtelephonic monitoring (TTM), for 12 months post procedure. Patients completed an Atrial Fibrillation Effect on Quality-of-life (AFEQT) questionnaire at their baseline and 12-month follow up visits. Results Majority (83.3% [274/329]) of patients experienced freedom from symptomatic atrial recurrence through 12 months. Of the 70 documented recurrences, 34 (49%) were documented by trans-telephonic monitoring only. All domains captured on the AFEQT questionnaire showed improvement with the overall score improving by 25.7, which exceeded the threshold of clinically meaningful improvement (±5) (Table). Patient reported most improvements in PAF control and symptoms relieved. The overall AFEQT score improvement was seen both in patients with or without documented atrial arrhythmia recurrence, with improvement by 21.5 and 26.8, respectively. Conclusion PAF ablation using a standardized CLOSE workflow resulted in consistent improvements in QoL. The improved QoL was observed regardless of atrial arrhythmia recurrence likely reflecting the low residual arrhythmia burden in patients with documented recurrence identified only on TTM. AFEQT Scores Through 12 Months AFEQT Domain Baseline 12 Months Change from Baseline* Daily Activities 59.2 85.3 26.0 Treatment Concerns 62.2 88.1 26.0 Controlling PAF 50.2 87.8 37.5 Symptoms 63.7 89.0 25.1 Symptoms Relieved 52.0 88.4 36.3 Overall AFEQT Score 61.3 87.2 25.7 *only includes patients who completed both baseline and 12 month AFEQT questionnaire

Flossing DNA in a Dual Nanopore Device.

Solid-state nanopores are a single-molecule technique that can provide access to biomolecular information that is otherwise masked by ensemble averaging. A promising application uses pores and barcoding chemistries to map molecular motifs along single DNA molecules. Despite recent research breakthroughs, however, it remains challenging to overcome molecular noise to fully exploit single-molecule data. Here, an active control technique termed "flossing" that uses a dual nanopore device is presented to trap a proteintagged DNA molecule and up to 100's of back-and-forth electrical scans of the molecule are performed in a few seconds. The protein motifs bound to 48.5 kb λ-DNA are used as detectable features for active triggering of the bidirectional control. Molecular noise is suppressed by averaging the multiscan data to produce averaged intertag distance estimates that are comparable to their known values. Since nanopore feature-mapping applications require DNA linearization when passing through the pore, a key advantage of flossing is that trans-pore linearization is increased to >98% by the second scan, compared to 35% for single nanopore passage of the same set of molecules. In concert with barcoding methods, the dual-pore flossing technique could enable genome mapping and structural variation applications, or mapping loci of epigenetic relevance.

Long-term impact of catheter ablation on arrhythmia burden in low-risk patients with paroxysmal atrial fibrillation: The CLOSE to CURE study

Few studies evaluated the impact of catheter ablation (CA) on atrial tachyarrhythmia (ATA) burden in paroxysmal atrial fibrillation (AF). In the prospective, patient-controlled CLOSE to CURE study, we determined the longer-term impact of optimized CA on ATA burden by using an insertable cardiac monitor (ICM). A total of 105 patients with paroxysmal AF were implanted with an ICM 65 (interquartile range [IQR] 61-78) days before CA. CA consisted of contact force-guided pulmonary vein isolation targeting an intertag distance of ≤6 mm and a region-specific ablation index. The primary end point was reduction in ICM-detected ATA burden; secondary end points were single-procedure freedom from ATA, quality of life, and adverse events. The mean age was 62 ± 8 years; the median CHA2DS2-VASc score was 1 (IQR 1-2); and the median left atrial diameter was 43 (IQR 39-43) mm. After pulmonary vein isolation (1.13 ± 0.39 procedures per patient), median ATA burden decreased from 2.68% (IQR 0.09%-15.02%) at baseline to 0% (IQR 0%-0%) during the first year and to 0% (IQR 0%-0%) during the second year (reduction in ATA burden 100% [IQR 100%-100%]; P < .001). Single-procedure freedom from any ATA was 87% at 1 year and 78% at 2 years. Quality of life improved significantly across all scores. Adverse events occurred in 5 patients (4.8%). CA has become an effective procedure in paroxysmal AF, with a major impact on ICM-detected ATA burden. Whereas conventional survival analysis suggests a progressive decline in efficacy, we observed that burden reduction is maintained at longer follow-up. These data imply that ATA burden is a more optimal end point for assessing ablation efficacy.

A Measurement Strategy to Assess the Optimal Design of an RFID-Based Navigation Aid

Different solutions have been proposed to address orientation in indoor/outdoor environments and among them, radio frequency identification (RFID)-based systems represent a strategic choice for its reduced complexity and cost. Widespread practices to validate the behavior of RFID-based systems use specific metrics related to the addressed application, while a general strategy to assess technical performances of the RFID-based system is lacking. In this paper, a novel measurement approach is proposed to perform optimal choices in developing an RFID-based orientation system and to impartially assess its technical performances. A multivariate measurement strategy is suggested to fully investigate performances of the system as a function of a set of operating quantities (user-tag distance, tag height, and intertag distance). An analysis is also proposed, which aims to assess the system performances in terms of sensitivity and specificity. Moreover, the use of a synthetic index, representing the overall behavior of the system under investigation is addressed. A case of study is presented. The system uses transparent RFID tags positioned in the environment and an embedded system including an RFID reader, as well as a dedicated module to convey audio messages to end-users. Results highlight that the device sensitivity improves in the case of a high intertag distance while the specificity decreases for short intertag distance, which is also confirmed by the synthetic index proposed. Specifically, an optimal tag height of 1 m has been estimated, while best performances are obtained in the case of intertag distance and user-tag distance belonging to ranges [1.50–2.50] m and [0.40–1.60] m, respectively.

Endoscopic evaluation of the esophagus after catheter ablation of atrial fibrillation using contiguous and optimized radiofrequency applications

The incidence of endoscopically detected esophageal lesions after pulmonary vein isolation (PVI) is as high as 18%. Intraesophageal temperature rise (ITR) during ablation is a predictor of esophageal injury. The purpose of this study was to describe an ablation strategy aiming to enclose the pulmonary veins with contiguous, stable, and optimized radiofrequency applications (referred to as CLOSE-PVI). We evaluated esophageal and periesophageal injury with endoscopy in patients revealing ITR during CLOSE-PVI. Eighty-five patients with ITR during CLOSE-PVI underwent endoscopy of the esophagus (with ultrasound in 38 patients). PVI consisted of contact force (CF)-guided encircling of the veins using 35-W applications, respecting strict criteria of intertag distance (≤6 mm) and ablation index (AI; 550 arbitrary unit [au] anterior wall, 400 au posterior wall, 300 au if ITR >38.5°C). Endoscopy was performed 9 ± 4 days after PVI. At the posterior wall, median power was 35 W [interquartile range (IQR) 35-35], application time 18 ± 5 seconds, CF 13 ± 6g, and AI 403 ± 38 au. A median of 5 applications [IQR 4-7] per patient over a length of 21.8 ± 6.8 mm resulted in ITR >38.5°C (median 39.9°C, IQR 39.2°C-41.2°C, range 38.6°C-50.0°C). For these applications, median power was 35 W [IQR 30-35], application time 14± 3 seconds, CF 12 ± 5g, and AI 351 ± 38 au. The incidence of esophageal erythema/erosion on endoscopy was 1 of 85 (1.2%) and of ulceration was 0 of 85 (0%). The incidence of mediastinal or esophageal injury on ultrasound was 0 of 38 (0%). The occurrence of esophageal or periesophageal injury after CLOSE-PVI is markedly low (1.2%). Absence of esophageal ulceration in patients with ITR suggests that this strategy of delivering contiguous, relatively high-power, and short-duration radiofrequency applications at the posterior wall is safe.

A Multipath Mitigation Localization Algorithm Based on MDS for Passive UHF RFID

Traditional localization algorithms are vulnerable in multipath environment for passive UHF RFID tag localization. To improve the localization accuracy, this letter proposes a robust algorithm named residual weighted multidimensional scaling (RWMDS) based on the multipath channel model. The RWMDS algorithm first utilizes reader-to-tag distances derived from received signal phase. To obtain the squared distance matrix required in the algorithm, the inter-tag distances are estimated using a few reference tags by establishing the relationship between inter-tag distance and phase information vectors measurement. Based on the modeling of ranging error in multipath environment, the RWMDS lgorithm can be applied to determine the estimated locations of the tags through a few iterations. Simulation results show that the RWMDS algorithm achieves higher localization accuracy than traditional algorithms in multipath environment.