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Hypertrophic cardiomyopathy (HCM) is the most prevalent inherited cardiomyopathy. The implantable cardioverter-defibrillator (ICD) is important for prevention of sudden cardiac death (SCD) in patients at high risk. In recent years, the subcutaneous implantable cardioverter-defibrillator (S-ICD) has emerged as a viable alternative to the transvenous implantable cardioverter-defibrillator (TV-ICD). The S-ICD does not require intravascular access; however, it cannot provide antitachycardia pacing (ATP) therapy.The purpose of this study was to assess the real-world incidence of ICD therapy in patients with HCM implanted with TV-ICD vs S-ICD.We compared the incidence of ATP and shock therapies among all HCM patients with S-ICD and TV-ICD enrolled in the Boston Scientific ALTITUDE database. Cumulative Kaplan-Meier incidence was used to compare therapy-free survival, and Cox proportional hazard ratios were calculated. We performed unmatched as well as propensity match analyses.We included 2047 patients with TV-ICD and 626 patients with S-ICD, followed for an average of 1650.5 ± 1038.5 days and 933.4 ± 550.6 days, respectively. Patients with HCM and TV-ICD had a significantly higher rate of device therapy compared to those with S-ICD (32.7 vs 14.5 therapies per 100 patient-years, respectively; P.001), driven by a high incidence of ATP therapy in the TV-ICD group, which accounted for67% of therapies delivered. Shock incidence was similar between groups, both in the general and the matched cohorts.Patients with HCM and S-ICD had a significantly lower therapy rate than patients with TV-ICD without difference in shock therapy, suggesting potentially unnecessary ATP therapy. Empirical ATP programming in patients with HCM may be unbeneficial.

Background More than 3 million cardiovascular implantable electronic devices (CIEDs) are implanted annually. There are minimal data regarding the timing of diagnosis of acute complications after implantation. It remains unclear whether patients can be safely discharged less than 24 hours postimplantation. Objective The purpose of this study was to determine the precise timing of acute complication diagnosis after CIED implantation and optimal timing for same-day discharge. Methods A retrospective cohort analysis of adults 18 years or older who underwent CIED implantation at a large urban quaternary care medical center between June 1, 2015, and March 30, 2020, was performed. Standard of care included overnight observation and chest radiography 6 and 24 hours postprocedure. Medical records were reviewed for the timing of diagnosis of acute complications. Acute complications included pneumothorax, hemothorax, pericardial effusion, lead dislodgment, and implant site hematoma requiring surgical intervention. Results A total of 2421 patients underwent implantation. Pericardial effusion or cardiac tamponade was diagnosed in 13 patients (0.53%), pneumothorax or hemothorax in 19 patients (0.78%), lead dislodgment in 11 patients (0.45%), and hematomas requiring surgical intervention in 5 patients (0.2%). Of the 48 acute complications, 43 (90%) occurred either within 6 hours or more than 24 hours after the procedure. Only 3 acute complications identified between 6 and 24 hours required intervention during the index hospitalization (0.12% of all cases). Conclusion Most acute complications are diagnosed either within the first 6 hours or more than 24 hours after implantation. With rare exception, patients can be considered for discharge after 6 hours of appropriate monitoring.

Patients with HIV infection have increased risk of atrial fibrillation, but the pathophysiologic mechanisms and the utility of catheter ablation in this population is not well-studied. We aimed to characterize outcomes of atrial fibrillation ablation and left atrial substrate in patients with HIV.The study was a retrospective propensity score-matched analysis of patients with and without HIV undergoing atrial fibrillation ablation. A search was performed in the electronic medical record for all patients with HIV who received initial atrial fibrillation ablation from 2011-2020. After calculating propensity scores for HIV, matching was performed with patients without HIV by using nearest neighbor matching without replacement in a 1:2 ratio. The primary outcome was freedom from atrial arrhythmia and secondary outcomes were freedom from atrial fibrillation, freedom from atrial tachycardia, and freedom from repeat ablation, compared by log-rank analysis. The procedures of patients with HIV who underwent repeat ablation at our institution were further analyzed for etiology of recurrence. To further characterize left atrial substrate, a subsequent case-control analysis was then performed for a set of randomly chosen ten patients with HIV matched with ten without HIV to compare minimum and maximum voltage at 9 pre-specified regions of the left atrium.27 patients with HIV were identified. All were prescribed antiretroviral therapy at time of ablation. These patients were matched with 54 patients without HIV by propensity score. 86.4% of patients with HIV and 76.9% of controls were free of atrial fibrillation or atrial tachycardia at one year (p=0.509). Log-rank analysis showed no difference in freedom from atrial arrhythmia (p-value 0.971), atrial fibrillation (p-value 0.346), atrial tachycardia (p-value 0.306), or repeat ablation (p-value 0.401) after initial atrial fibrillation ablation in patients with HIV compared to patients without HIV. In patients with HIV with recurrent atrial fibrillation, the majority had pulmonary vein reconnection (67%). There were no significant differences in minimum or maximum voltage at any of the nine left atrial regions between the matched patients with and without HIV.Ablation to treat atrial fibrillation in patients with HIV, but without overt AIDS is frequently successful therapy. The majority of patients with recurrence of atrial fibrillation had pulmonary vein reconnection, suggesting infrequent non-pulmonary vein substrate. In this population the left atrial voltage in patients with HIV is similar to that of patients without HIV. These findings suggest that the pulmonary veins remain a critical component to the initiation and maintenance of atrial fibrillation in patients with HIV. This article is protected by copyright. All rights reserved.

OBJECTIVE To compare multiple-procedure catheter ablation outcomes of a stepwise approach versus left atrial posterior wall isolation (LA PWI) in patients undergoing nonparoxysmal atrial fibrillation (NPAF) ablation. BACKGROUND Unfavorable outcomes for stepwise ablation of NPAF in large clinical trials may be attributable to proarrhythmic effects of incomplete ablation lines. It is unknown if a more extensive initial ablation strategy results in improved outcomes following multiple ablation procedures. METHODS Two hundred twenty two consecutive patients with NPAF underwent first-time ablation using a contact-force sensing ablation catheter utilizing either a stepwise (Group 1, n = 111) or LA PWI (Group 2, n = 111) approach. The duration of follow-up was 36 months. The primary endpoint was freedom from atrial arrhythmia >30 s. Secondary endpoints were freedom from persistent arrhythmia, repeat ablation, and recurrent arrhythmia after repeat ablation. RESULTS There was similar freedom from atrial arrhythmias after index ablation for both stepwise and LA PWI groups at 36 months (60% vs. 69%, p = .1). The stepwise group was more likely to present with persistent recurrent arrhythmia (29% vs. 14%, p = .005) and more likely to undergo second catheter ablation (32% vs. 12%, p

Conducted energy weapon (commonly known as TASER) discharge in patients with implantable cardioverter-defibrillators is known to cause electromagnetic interference and inappropriate ventricular fibrillation sensing without delivery of implantable cardioverter-defibrillators therapy during conducted energy weapon application. We report the first known case of conducted energy weapon discharge resulting in inappropriate implantable cardioverter-defibrillators therapy. (Level of Difficulty: Beginner.), Graphical abstract, Conducted energy weapon (commonly known as TASER) discharge in patients with implantable cardioverter-defibrillators is known to cause electromagnetic…

Background Increased peak luminal esophageal temperature (LET) is associated with increased risk of esophageal injury after left atrial posterior wall (LAPW) ablation. The magnitude, distribution, and risk factors of LET increase with high-power short-duration (HPSD) LAPW ablation are not well understood. Objective The purpose of this study was to describe the spatial and temporal characteristics of LET changes associated with HPSD LAPW radiofrequency (RF) ablation. Methods LET was sampled at 20 Hz using a 12-point esophageal temperature monitor (CIRCA S-CATH; Circa Scientific, Inc) in 16 patients undergoing LAPW ablation. Esophageal temperature sensor position and lesion locations were recorded using an electroanatomic mapping system with fluoroscopic integration (CARTO 3, CARTOUNIVU; Biosense Webster, Inc). Point-by-point LAPW ablation was performed at 50 W for 6 seconds. The first 20 LAPW lesions were individually analyzed in each patient. Results LET increase ≥4°C (8 lesions: max LET 5.8°C), 2°–4°C (34 lesions), and 1°–2°C (58 lesions) occurred at 9 ± 2 mm, 8 ± 2 mm, and 13 ± 2 mm from sensors, respectively. Lesions placed >20 mm from a temperature sensor did not result in an LET increase ≥2°C. Temperature resolution to within 1°C of baseline occurred ∼60 seconds after cessation of RF application. Consecutive lesions resulting in additive heating of at least 1°C occurred in 17 lesion pairs with an interlesion distance of 9 ± 4 mm and interlesion time of 21 ± 4 seconds. Conclusion HPSD LAPW ablation can result in severe esophageal temperature increases. Significant LET increase will be undetected when lesions are >20 mm away from a temperature sensor. Additive LET increase was observed with consecutive lesions placed

Prior studies have shown that addition of posterior wall isolation (PWI) may reduce atrial fibrillation recurrence in patients with persistent atrial fibrillation. No data on PWI in paroxysmal AF (pAF) patients with normal left atrial voltage is available, to date.This study sought to evaluate the efficacy of PWI in addition to pulmonary vein isolation (PVI) in patients presenting with pAF and normal left atrial voltage.Consecutive patient registry analysis was performed on all patients with pAF and normal left atrial voltage undergoing initial radiofrequency ablation from November 1, 2018 to November 15, 2019. Primary endpoint was recurrence of atrial arrhythmia including AF, atrial tachycardia (AT), or atrial flutter (AFL).A total of 321 patients were studied, 214 in the PVI group and 107 in the PWI + PVI group. Recurrence of any atrial arrhythmia occurred in 18.2% of patients in the PVI group and 16.8% in the PVI + PWI cohort (p = 0.58). At 1 year, recurrence was 14.0% in the PVI group and 15.0% in the PWI + PVI group (p = 0.96). There was a lower AT/AFL recurrence in the PVI + PWI group, not reaching significance (3.7% in the PWI + PVI group vs. 7.9% in PVI group, p = 0.31). Need for carina lesions predicted recurrence in the PVI-only group.Addition of PWI to PVI in pAF patients undergoing their first ablation did not reduce the frequency of atrial arrhythmia recurrence. This warrants further study in a prospective trial.

This article reviews and compares the rationale and evidence supporting high-power, short-duration radiofrequency (RF) ablation with those of conventional-power, conventional-duration RF ablation for atrial fibrillation (AF). The pros and cons of each approach, biophysics of ablation, pre-clinical studies informing clinical utilization, and the accumulated clinical evidence are presented. Both conventional-power, conventional-duration RF ablation and high-power, short-duration ablation are similarly safe, and effective approaches for AF ablation. Theoretical advantages of high-power, short-duration ablation, including greater procedure efficiency and limited conductive heating of collateral structures, must be weighed against the narrower safety margin related to rapid energy delivery during high power ablation.

Clinical trials have failed to reliably show improved outcomes with utilization of contact-force sensing (CFS) radiofrequency (RF) ablation catheters. It is unknown whether the unfavorable outcomes observed in these trials are attributable to inexperience with CFS technology. To compare catheter ablation outcomes of stepwise linear ablation with versus without CFS technology and to assess the impact of operator experience with CFS technology on procedural outcomes. Clinical outcomes were evaluated in 228 consecutive NPAF patients undergoing first-time left atrial ablation using a stepwise linear approach. Arrhythmia recurrence was assessed using 2-week event monitors at 3-month intervals following index ablation. A total of 228 patients were included in our study. There was no statistically significant difference in risk of recurrent atrial arrhythmias at 12 and 24 months between CFS and non-CFS patients (p = 0.5 and p = 0.169). The time to recurrence of atrial arrhythmias at 24 months in the second half of CFS patients was significantly lower when compared to both the first half of CFS patients (p = 0.002) and non-CFS patients (p = 0.005). While there was no difference in overall outcomes between CFS and non-CFS ablation using a stepwise linear approach in patients with NPAF, procedural efficacy of the second half of CFS patients was significantly improved compared to both the first half of CFS patients and all non-CFS patients. Lack of benefit seen in clinical trials using CFS technology may be related to operator inexperience with CFS ablation catheters at the time of the trials.

Purpose Catheter ablation procedures for atrial fibrillation (AF) were significantly curtailed during the peak of coronavirus disease 2019 (COVID-19) pandemic to conserve healthcare resources and limit exposure. There is little data regarding peri-procedural outcomes of medical procedures during the COVID-19 pandemic. We enacted protocols to safely reboot AF ablation while limiting healthcare resource utilization. We aimed to evaluate acute and subacute outcomes of protocols instituted for reboot of AF ablation during the COVID-19 pandemic. Methods Perioperative healthcare utilization and acute procedural outcomes were analyzed for consecutive patients undergoing AF ablation under COVID-19 protocols (2020 cohort; n=111) and compared to those of patients who underwent AF ablation during the same time period in 2019 (2019 cohort; n=200). Newly implemented practices included preoperative COVID-19 testing, selective transesophageal echocardiography (TEE), utilization of venous closure, and same-day discharge when clinically appropriate. Results Pre-ablation COVID-19 testing was positive in 1 of 111 patients. There were 0 cases ablation-related COVID-19 transmission and 0 major complications in either cohort. Pre-procedure TEE was performed in significantly fewer 2020 cohort patients compared to the 2019 cohort patients (68.4% vs. 97.5%, p

Background: Hypertrophic cardiomyopathy (HCM) is the most prevalent inherited cardiomyopathy. Implantable Cardioverter Defibrillator (ICD) is important for prevention of sudden cardiac death (SCD) in patients at high risk. In recent years the subcutaneous ICD (S-ICD) has emerged as a viable alternative to the transvenous ICD (TV-ICD). The S-ICD does not require intravascular access, but cannot provide antitachycardia pacing therapy (ATP). Objective: To assess the real world incidence of ICD therapy in patients with HCM implanted with TV-ICD versus S-ICD.Methods: We compared the incidence of ATP and shock therapies between all HCM patients with S-ICD and TV-ICD enrolled in the Boston Scientific ALTITUDE database. Cumulative Kaplan Meier incidence was used to compare therapy free survival and Cox proportional hazard ratios were calculated. We performed an unmatched as well as propensity match analysis. Results: We included 2462 patients with TV-ICD and 716 patients with S-ICD followed for an average of 1348 {plus minus} 989 days. Patients with HCM and TV-ICD had significantly higher rate of device therapy as compared to those with S-ICD (31.1 vs. 14.7 therapies /100 patient year; p

Background: The COVID-19 pandemic has resulted in worldwide morbidity at unprecedented scale. Troponin elevation is a frequent laboratory finding in hospitalized patients with the disease, and may reflect direct vascular injury or non-specific supply-demand imbalance. In this work, we assessed the correlation between different ranges of Troponin elevation, Electrocardiographic (ECG) abnormalities, and mortality.Methods: We retrospectively studied 204 consecutive patients hospitalized at NYU Langone Health with COVID-19. Serial ECG tracings were evaluated in conjunction with laboratory data including Troponin. Mortality was analyzed in respect to the degree of Troponin elevation and the presence of ECG changes including ST elevation, ST depression or T wave inversion.Results: Mortality increased in parallel with increase in Troponin elevation groups and reached 60% when Troponin was >1 ng/ml. In patients with mild Troponin rise (0.05–1.00 ng/ml) the presence of ECG abnormality and particularly T wave inversions resulted in significantly greater mortality.Conclusion: ECG repolarization abnormalities may represent a marker of clinical severity in patients with mild elevation in Troponin values. This finding can be used to enhance risk stratification in patients hospitalized with COVID-19.

Backgroundthe COVID19 pandemic has resulted in worldwide morbidity at unprecedented scale. Troponin elevation is a frequent laboratory finding in hospitalized patients with the disease, and may reflect direct vascular injury or nonspecific supply-demand imbalance. In this work, we assessed the correlation between different ranges of Troponin elevation, Electrocardiographic (ECG) abnormalities and mortality.MethodsWe retrospectively studied 204 consecutive patients hospitalized at NYU Langone Health with COVID19. Serial ECG tracings were evaluated in conjunction with laboratory data including Troponin. Mortality was analyzed in respect to the degree of Troponin elevation and the presence of ECG changes including ST elevation, ST depression or T wave inversion.ResultsMortality increased in parallel with increase in Troponin elevation groups and reached 60% when Troponin was >1 ng/ml. In patients with mild Troponin rise (0.05 – 1.00 ng/ml) the presence of ECG abnormality resulted in significantly greater mortality.ConclusionECG repolarization abnormalities may represent a marker of clinical severity in patients with mild elevation in Troponin values. This finding can be used to enhance risk stratification in patients hospitalized with COVID19.

Introduction: Left atrial posterior wall (LAPW) isolation is associated with favorable outcomes for catheter ablation of persistent atrial fibrillation (PEAF). Techniques for LAPW isolation include ablation at the periphery with or without high density ablation within the LAPW. The proportion of LA isolated by the lesion set also varies greatly. The optimal technique to achieve LAPW isolation is not clear. Objective: To assess impact of ablation lesion density within and dimensions of the LAPW isolation region on arrhythmia recurrence in catheter ablation of PEAF. Methods: LAPW lesion density and surface area relative to total LA surface area were calculated using electroanatomic maps of 110 consecutive patients undergoing LAPW isolation for PEAF (CARTO 3, Biosense Webster, Inc.). LAPW isolation was performed at the discretion of 5 experienced operators after voltage mapping. LAPW PV entrance and exit block were confirmed. Arrhythmia recurrence at two years was assessed by Kaplan-Meier analysis. Results: LAPW lesion density ranged from 0% - 99%. The proportion of LA surface area isolated ranged from 35% - 75%. There was no significant difference in arrhythmia-free survival stratified by median LAPW ablation density (31% vs. 27%, p=0.8) or median proportion of electrically-isolated LA surface area (31% vs. 27%, p=0.8%). Voltage map-guided LAPW isolation did not significantly decrease arrhythmia recurrence (29% vs. 28%, p=1). Conclusion: Neither the density of ablation within nor the dimensions of the LAPW isolated region predicted arrhythmia-free survival for catheter ablation of PEAF. Voltage map-guided LAPW isolation resulted in similar ablation efficacy regardless of LA scar burden.

BackgroundThe emergence of the COVID-19 pandemic has resulted in over two million affected and over 150 thousand deaths to date. There is no known effective therapy for the disease. Initial reports suggesting the potential benefit of Hydroxychloroquine/Azithromycin (HY/AZ) have resulted in massive adoption of this combination worldwide. However, while the true efficacy of this regimen is unknown, initial reports have raised concerns regarding the potential risk of QT prolongation and induction of torsade de pointes (TdP).MethodsThis is a multicenter retrospective study of 251 patients with COVID-19 treated with HY/AZ. We reviewed ECG tracings from baseline and until 3 days after completion of therapy to determine the progression of QTc and incidence of arrhythmia and mortality.ResultsQTc prolonged in parallel with increasing drug exposure and incompletely shortened after its completion. Extreme new QTc prolongation to > 500 ms, a known marker of high risk for TdP had developed in 15.9% of patients. One patient developed TdP requiring emergent cardioversion. Seven patients required premature termination of therapy. The baseline QTc of patients exhibiting QTc prolongation of > 60 ms was normal.ConclusionThe combination of HY/AZ significantly prolongs the QTc in patients with COVID-19. This prolongation may be responsible for life threating arrhythmia in the form of TdP. This risk mandates careful consideration of HY/AZ therapy in lights of its unproven efficacy. Strict QTc monitoring should be performed if the regimen is given.

Elimination of pace-capture along pulmonary vein isolation (PVI) lesion sets reduces atrial fibrillation (AF) recurrence in catheter ablation of paroxysmal AF. Pacing from the RF ablation electrode during RF application is prevented within the CARTO electroanatomic mapping system (Biosense Webster, Inc.) due to theoretical safety considerations. We evaluated a method of pacing the distal ablation electrode during RF application in the CARTO system, thus avoiding repeated activation and inactivation of the pacing channel and facilitating immediate recognition of pace-capture loss. We investigated the safety, feasibility, and utility of simultaneous pace-ablate (SPA) during AF ablation with the CARTO-3 system and a contact-force sensing RF ablation catheter. Safety of feasibility of SPA was evaluated in 250 patients undergoing first-time AF ablation. Frequency and regional distribution of pace-capture following PVI was evaluated in a cohort of 50 consecutive patients undergoing catheter ablation of paroxysmal AF. SPA was successfully performed in all 250 patients without adverse event. At least one pace-capture site was noted in 22 of 50 PAF patients (44%), and pace-capture following PVI was most common at anterior and superior left atrial sites. There were 2.0 ± 3.3 RF applications during pacing via the distal ablation electrode per patient, and all lesions sets were successfully rendered unexcitable. Pace-capture along the completed PVI lesion set remains common despite utilization of contact-force sensing RF ablation catheters and automated lesion annotation. Simultaneous pace-ablate in AF ablation using the CARTO system may be safely used to render atrial lesion sets unexcitable.

ECG Waveform Analysis in Atrial Tachycardias Introduction Atrial fibrillation (AF) ablation patients often manifest atrial tachycardias (AT) with atypical ECG morphologies that preclude accurate localization and mechanism. Diagnostic maneuvers used to define ATs during electrophysiology studies can be limited by tachycardia termination or transformation. Additional methods of characterizing post-AF ablation ATs are required. Methods and Results We evaluated the utility of noninvasive ECG signal analytics in postablation AF patients for the following features: (1) Localization of ATs (i.e., right vs. left atrium), and (2) Identification of common left AT mechanisms (i.e., focal vs. macroreentrant). Atrial waveforms from the surface ECG were used to analyze (1) spectral organization, including dominant amplitude (DA) and mean spectral profile (MP), and (2) temporospatial variability, using temporospatial correlation coefficients. We studied 94 ATs in 71 patients who had undergone prior pulmonary vein isolation for AF and returned for a second ablation: (1) right atrial cavotricuspid-isthmus dependent (CTI) ATs (n = 21); (2) left atrial macroreentrant ATs (n = 41) and focal ATs (n = 32). Right CTI ATs manifested higher DAs and lower MPs than left ATs, indicative of greater stability and less complexity in the frequency spectrum. Left macroreentrant ATs possessed higher temporospatial organization than left focal ATs. Conclusions Noninvasively recorded atrial waveform signal analyses show that right ATs possess more stable activation properties than left ATs, and left macroreentrant ATs manifest higher temporospatial organization than left focal ATs. Further prospective analyses evaluating the role these novel ECG-derived tools can play to help localize and identify mechanisms of common ATs in AF ablation patients are warranted.

Background There are scant data comparing the electrogram (EGM) signal characteristics of atrial fibrillation (AF) at baseline vs electrically induced states during ablation procedures. Objective The purpose of this study was to use novel intracardiac signal analysis techniques to gain insights into the effects of catheter ablation and AF reinduction on AF EGMs in patients with persistent AF. Methods We collected left atrial EGMs in patients undergoing first ablation for persistent AF at 3 time intervals: (1) AF at baseline; (2) AF after pulmonary vein isolation (PVI); and (3) AF after post-PVI cardioversion and subsequent reinduction. We analyzed 2 EGM spectral characteristics: (1) dominant frequency and (2) spectral complexity; and 2 EGM morphologic characteristics: (1) morphology variation and (2) pattern repetitiveness. Results There were no differences in AF dominant frequency, dominant amplitude, spectral complexity, or metrics of EGM morphology or repetitiveness at baseline vs after PVI. However, dominant frequency, dominant amplitude, and spectral complexity differed significantly after direct current cardioversion and reinduction of AF. Conclusion The frequency, spectral complexity, and local EGM morphologies of AF do not significantly change over the course of a PVI procedure in patients with persistent AF. However, reinduction of AF after direct current cardioversion results in different dominant frequency and spectral complexity, consistent with a change in the characteristics of the perpetuating source(s) of the newly induced AF. These data suggest that AF properties can vary significantly between baseline and reinduced AF, with potential clinical ramifications for outcomes of catheter ablation procedures.

The advance of transportation technology depends on science and economics. During the 1930s, airships and airplanes competed head-to-head for the Atlantic passenger market. When World War 2 broke out, everything changed. Over the next five years, the combined combatants built over half of a million military airplanes. By the end of the war, four-engine, high-altitude bombers and jet engines were developed. Further investment in airplane technology was stimulated by the Cold War. All this public investment was adapted to civilian passenger jet airplanes. By 1980, dedicated jet airplanes were in use as cargo carriers. Despite the growth of the cargojet market over the past three decades, rising fuel costs and environmental concerns are changing the economics of airships and airplanes again. Investment in large cargo airships is returning. Much of the technology developed for fixed-wing aircraft can be applied to cargo airships. New materials, better engines, control systems and engineering eliminate the need for large ground crews and improve airship reliability and safety. However, two fundamental design issues have yet to be resolved: structural integrity and buoyancy control. A worldwide competition is underway on three continents to develop the dominant design for a cargo airship. This paper examines the alternative design approaches and presents the status of the international competition.

Atrial fibrillation (AF) ablation patients often manifest atrial tachycardias (AT) with atypical ECG morphologies that preclude accurate localization and mechanism. Diagnostic maneuvers used to define ATs during electrophysiology studies can be limited by tachycardia termination or transformation. Additional methods of characterizing post-AF ablation ATs are required.We evaluated the utility of noninvasive ECG signal analytics in postablation AF patients for the following features: (1) Localization of ATs (i.e., right vs. left atrium), and (2) Identification of common left AT mechanisms (i.e., focal vs. macroreentrant). Atrial waveforms from the surface ECG were used to analyze (1) spectral organization, including dominant amplitude (DA) and mean spectral profile (MP), and (2) temporospatial variability, using temporospatial correlation coefficients. We studied 94 ATs in 71 patients who had undergone prior pulmonary vein isolation for AF and returned for a second ablation: (1) right atrial cavotricuspid-isthmus dependent (CTI) ATs (n = 21); (2) left atrial macroreentrant ATs (n = 41) and focal ATs (n = 32). Right CTI ATs manifested higher DAs and lower MPs than left ATs, indicative of greater stability and less complexity in the frequency spectrum. Left macroreentrant ATs possessed higher temporospatial organization than left focal ATs.Noninvasively recorded atrial waveform signal analyses show that right ATs possess more stable activation properties than left ATs, and left macroreentrant ATs manifest higher temporospatial organization than left focal ATs. Further prospective analyses evaluating the role these novel ECG-derived tools can play to help localize and identify mechanisms of common ATs in AF ablation patients are warranted.