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Background Limited data on the efficacy and safety of atrial fibrillation (AF) ablation using an ablation index (AI) for octogenarians is available. We aimed to compare the efficacy and safety of AI‐guided AF ablation between AF patients aged ≥80 years (Group 1) and <80 (Group 2). Hypothesis We hypothesized that AI‐guided AF ablation could complete the procedure with comparable efficiency and safety in patients aged ≥80 years and <80. Methods We retrospectively reviewed 2087 AF patients undergoing their first AI‐guided AF ablation in our hospital. We compared the atrial tachyarrhythmia (AT) recurrence and procedure‐related complication rate between Group 1 (n = 193) and Group 2 (n = 1894). Results The mean age was 83.0 (interquartile range [IQR] 81.0, 84.0) years in Group 1 and 67.0 (IQR 60.0, 72.0) in Group 2. AF type was significantly different between the two groups: Of Group 1 patients, 120 (62.2%) had paroxysmal AF, 61 (31.6%) persistent AF, and 12 (6.2%) long‐standing persistent AF, while of Group 2 patients, 1016 (53.6%) paroxysmal AF, 582 (30.7%) persistent AF, and 296 (15.6%) long‐standing persistent AF (p = .001). Unadjusted AT recurrence‐free survival curves showed similar AT recurrence‐free survival between the two groups (p = .67 by log‐rank test). After the adjustment for AF type, the survival curve was similar between them (hazard ratio, 1.24; 95% CI [0.92–1.65]; p = .15, Group 1 vs. Group 2). The rate of procedure‐related complications was similar between the two groups (3.1% vs. 3.0%, respectively, p = .83). Conclusion Catheter ablation guided by AI achieved similar AT recurrence and complication rates between elderly AF patients aged ≥80 years and patients <80 years. Catheter ablation guided by the ablation index achieved a similar AT recurrence rate between elderly AF patients aged ≥80 years and patients <80 years. The overall complication rate was similar among them. However, the percentage of cardiac tamponade in AF patients aged ≥80 years was almost three times as high as those <80 years.

Abstract Background Complex fractionated atrial electrogram (CFAE)-targeted catheter ablation (CFAE ablation) requires a high rate of atrial fibrillation (AF) termination to provide good outcomes. We determined the optimal settings of CFAE software. Methods In our 430 consecutive patients, AF was terminated in 97 (234/242) and 79% (149/188) of patients with paroxysmal and persistent AF, respectively, by CFAE ablation combined with (31%) or without (69%) pulmonary vein isolation, occasionally with nifekalant infusion. We analyzed 109 consecutive patients who underwent CFAE ablation to determine the optimal settings for comparing subjective versus objective decisions by the CFAE software on CARTO3. We compared three settings: the default setting (0.05–0.15 mV, 50–120 ms) and two modified settings (#1: 0.05–0.30 mV, 40–70 ms, #2: 0.05–0.13 mV, 10–20 ms). We retrospectively analyzed 11,425 points during left atrial mapping before ablation and 10,306 points that were subjectively detected and ablated as CFAE points. An interval confidence level ≥6 denoted a site with CFAE. Results With the default setting, the accuracy, sensitivity, specificity, positive productive value, and negative productive values were 67, 42, 77, 48, and 73%, respectively. With modified setting #1, the values were 78, 55, 87, 74, and 77%, respectively, versus 64, 82, 60, 53, and 91%, respectively, for modified setting #2. Conclusion These data suggest that setting #1 was generally superior to the default setting, whereas setting #2 was optimal for excluding areas not requiring ablation. The optimal CFAE software setting was a voltage of 0.05–0.30 mV and an interval parameter of 40–70 ms.

Background Confluent inferior pulmonary veins (CIPV) is a rare anatomical variant. There is few evidence in the literature regarding anatomic landmarks consideration to guide radiofrequency application in avoiding complications in the esophagus in CIPV cases. Methods Of 986 consecutive patients undergoing atrial fibrillation (AF) ablation from July 2020 to June 2022, seven (0.7%) had CIPV with a common trunk connecting to the LA diagnosed by 3-dimensional contrast-enhanced computed tomography. Using intracardiac echocardiography (ICE) performed from the left atrium (LA), we measured the posterior wall thickness (PWT) of the CIPV adjacent to the esophagus and compared the measurement with the LA posterior wall thickness (LAPWT) at the left inferior PV level of 25 controls without CIPV. For ablation in CIPV patients, each superior PV was individually isolated, and box isolation of CIPV without ablating the CIPV posterior wall was added (tri-circle ablation technique). Results The CIPV PWT was 0.7 ± 0.1 mm, while non-CIPV LAPWT was 2.0 ± 0.4 mm ( P  < 0.001). In the CIPV group, upper and lower portions of the CIPV were both apart from the esophagus (mean distances, 6.7 ± 3.4 mm and 7.9 ± 2.7 mm, respectively). Individual superior PV isolation and box CIPV isolation resulted in complete isolation of all PVs, with no complications. All CIPV patients except one remained AF recurrence-free for 376 ± 52 days. Conclusions Although CIPV frequency is low, CIPV PWT is very thin and special care is needed during ablation. A “tri-circle” ablation strategy avoids ablating in the thinnest portion of the posterior wall. Further studies are warranted to assess the safety.

Sea ice can be interspersed vertically with both permeable and impermeable layers. These features can be smaller than a few centimetres but are important for understanding biogeochemical cycles in sea ice. Traditionally, sea-ice samples are collected by drilling into the ice with a rotating core barrel with a cutting head. Ice cores are extracted and then cut into sections that are melted to collect the variable of interest. Drawbacks to this method include difficulty cutting sections smaller than a few centimetres thick and contamination of samples. Brines may also drain from their in-situ locations and be lost, meaning that important micro-environments in sea ice may be overlooked or misrepresented. To address these drawbacks, we developed a sea-ice melt probe that bores into sea ice and collects high-resolution samples. The capability of the melt probe to delineate a layer of dye in artificial sea ice was tested during cold laboratory-based experiments. Complementary field experiments were carried out in first-year landfast sea ice during February–March 2023 at Saroma-ko Lagoon, Japan. Experiments consisted of testing the high-vertical-resolution capability of the melt probe as well as its ability to be deployed on snow-covered sea ice. The melt probe was able to delineate a layer of dye at a finer resolution (20 mm) than traditional ice coring (approximately 50–100 mm) and could sample sea-ice brine in the field at a high vertical resolution. Melt-probe samples were also used to measure iron in sea ice without contamination. This proof-of-concept study provides an alternative method of sampling sea ice with the ability to support new research on fine-scale structures, with applications for sampling dissolved and particulate sea-ice constituents including trace metals, macro-nutrients, microplastics and gases.

Formosan subterranean termites, Coptotermes formosanus, tend to avoid pathogen odors when tested in Y-tube olfactometers, but approach and groom exposed nestmates to remove pathogens from their cuticle and maintain a healthy population. To better understand their differential reaction to pathogens and their odors, the relationship between odor cues and direction of motion was examined with the fungus Isaria fumosorosea K3 strain. The results indicate that nestmate odor was strongly attractive only in tests where fungal odors were present in both branches of the olfactometer. Termites generally avoid fungal odors when offered a choice without fungal odor. We also tested termite aversion to 3-octanone and 1-octen-3-ol, major surface chemical compounds of I. fumosorosea K3, and estimated the total mass of these compounds present on the conidial surface by direct extraction method. The total quantity of these chemicals on the surface of fungal conidia was estimated to be approximately 0.01 ng per 10⁷ conidia. This study demonstrates a context dependent behavioral change in termites in response to the odors of pathogenic fungi.

The results of biocontrol with entomopathogens in termites have been discouraging because of the strong social hygiene behavior for removing pathogens from termite colonies. However, the mechanism of pathogen detection is still unclear. For the successful application of biopesticides to termites in nature, it would be beneficial to identify substances that could disrupt the termite's ability to perceive pathogens. We hypothesized that termites can perceive pathogens and this ability plays an important role in effective hygiene behavior. In this study, pathogen-detection in the subterranean termite Coptotermes formosanus was investigated. We performed quantitative assays on conidia removal by grooming behavior using epifluoresence microscopy and Y-maze tests to examine the perception of fungal odor by termites. Three species each of high- and low-virulence entomopathogenic fungi were used in each test. The results demonstrated that termites removed conidia more effectively from a nestmate's cuticle if its odor elicited stronger aversion. Highly virulent pathogens showed higher attachment rates to termite surfaces and their odors were more strongly avoided than those of low-virulence isolates in the same species. Moreover, termites appeared to groom each other more persistently when they had more conidia on their bodies. In brief, insect perception of pathogen-related odor seems to play a role in the mechanism of their hygiene behavior.