Differential Pacing Maneuver From the Vein of Marshall.

BACKGROUND: Bidirectional mitral isthmus (MI) block is conventionally verified by differential pacing from the coronary sinus (CS) and its sequence change. This study aimed to evaluate the ability of differential pacing from the vein of Marshall (VOM) to detect epicardial MI connections. METHODS: Radiofrequency and VOM ethanol MI ablation were performed with a VOM electrode catheter inserted to the septal side of the ablation line. MI block was verified using conventional CS pacing. To perform differential VOM pacing analysis, initial pacing was delivered from a distal VOM bipole closer to the block line, and then from a proximal VOM bipole. The intervals from pacing stimulus during different VOM pacing sites to the electrogram recorded through the CS catheter on the opposite side of the line were compared. When the interval during distal VOM pacing was longer than that during proximal VOM pacing, it indicated a VOM connection block; however, if the former interval was shorter, the connection through the VOM was considered persistent. RESULTS: Overall, 50 patients were evaluated. According to CS pacing, MI ablation was incomplete in 9 patients, in whom the analysis indicated persistent VOM connection. Among 41 patients with complete MI block, confirmed by CS finding, in 30 (73%) patients, the interval during distal VOM pacing was longer than that during proximal VOM pacing by 11±5 ms. However, in 11 patients (27%) the former interval was revealed to be shorter than the latter by 16±8 ms, indicating residual VOM connection. Conduction time across the line was significantly shorter in 11 patients than in the other 30 (166±21 versus 197±36 ms; P<0.01). Ten successful reevaluated analyses after VOM ethanol and further radiofrequency ablation of the connection indicated VOM block achievement. CONCLUSIONS: Differential VOM pacing maneuver reflects the VOM conduction status. This maneuver can uncover residual epicardial connections that are missing with CS pacing.

Posterior wall thickness of the confluent inferior pulmonary veins measured by left atrial intracardiac echocardiography: implications for catheter ablation.

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.

Predictors of pulmonary vein non-reconnection in the second procedure after ablation index-guided pulmonary vein isolation for atrial fibrillation and its impact on the outcome.

INTRODUCTION: Although first-pass isolation (FPI) of the pulmonary vein (PV) has been suggested as a marker for PV isolation (PVI) durability, it has not been confirmed. Non-PV atrial fibrillation (AF) triggers were the main target in patients without PV reconnection in the second ablation procedure, but the outcome was unclear. We aimed to validate FPI as a marker of PVI durability and evaluate the outcome after the second procedure in patients without PV reconnection by comparing it to those with reconnection. METHODS: Among the 2087 patients undergoing the first ablation index-guided radiofrequency AF ablation, 309 with atrial tachyarrhythmias (ATs) recurrence and undergoing the second procedure were studied. Clinical characteristics and outcomes were compared between the patients without PV reconnection (PV non-reconnection group, n = 142) and with reconnection (PV reconnection group, n = 167). RESULTS: FPI in both PV sides in the first ablation procedure was significantly more frequent in the PV non-reconnection group (77.5%) than in the PV reconnection group (45.5%) (p < .001). Multivariate logistic regression analysis revealed that FPI (odds ratio, 3.71 [95% confidence interval, 2.23-6.19], p < .001) was the only predictor of PV non-reconnection. Radiofrequency applications for non-PV AF triggers were more frequently performed in the PV non-reconnection group (40.8% vs. 24.6%, respectively, p < .001). Kaplan-Meier analysis revealed that AT recurrence-free rate was significantly lower in the PV non-reconnection group (1-year recurrence-free rate, 62.7% vs. 75.4%, respectively; p = .01 by log-rank test). CONCLUSION: FPI was the only independent predictor of PV non-reconnection. Despite aggressive ablation for non-PV triggers, AT recurrence was more frequent in patients with PV non-reconnection.

Safety and efficacy of ablation index-guided atrial fibrillation ablation in octogenarians.

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.

Peri-procedural anticoagulation in patients with end-stage kidney disease undergoing atrial fibrillation ablation: results from the multicentre end-stage kidney disease-atrial fibrillation ablation registry.

AIMS: The optimal anticoagulation regimen in patients with end-stage kidney disease (ESKD) undergoing atrial fibrillation (AF) catheter ablation is unknown. We sought to describe the real-world practice of peri-procedural anticoagulation management in patients with ESKD undergoing AF ablation. METHODS AND RESULTS: Patients with ESKD on haemodialysis undergoing catheter ablation for AF in 12 referral centres in Japan were included. The international normalized ratio (INR) before and 1 and 3 months after ablation was collected. Peri-procedural major haemorrhagic events as defined by the International Society on Thrombosis and Haemostasis, as well as thromboembolic events, were adjudicated. A total of 347 procedures in 307 patients (67 ±9 years, 40% female) were included. Overall, INR values were grossly subtherapeutic [1.58 (interquartile range: 1.20-2.00) before ablation, 1.54 (1.22-2.02) at 1 month, and 1.22 (1.01-1.71) at 3 months]. Thirty-five patients (10%) suffered major complications, the majority of which was major bleeding (19 patients; 5.4%), including 11 cardiac tamponade (3.2%). There were two peri-procedural deaths (0.6%), both related to bleeding events. A pre-procedural INR value of 2.0 or higher was the only independent predictor of major bleeding [odds ratio, 3.3 (1.2-8.7), P = 0.018]. No cerebral or systemic thromboembolism occurred. CONCLUSION: Despite most patients with ESKD undergoing AF ablation showing undertreatment with warfarin, major bleeding events are common while thromboembolic events are rare.

The relationship between scapular position and glenohumeral rotational range of motion in high school baseball players.

BACKGROUND: Past research indicated that scapular malposition is related to the glenohumeral internal rotation deficit (GIRD). However, there is no research examining the effect of throwing-related pain on this relationship. This study investigated the relationship between scapular position and range of motion (ROM) and compared the difference in this relationship between with and without throwing-related pain. METHODS: Forty male baseball players in high school were recruited for this study. The existence and degree of throwing-related pain were obtained from a questionnaire. Participants were divided into 2 groups according to the presence or absence of the pain. Glenohumeral internal and external rotation ROM (abduction internal rotation angle and abduction external rotation angle [ABER], respectively) were measured using a digital inclinometer. The pectoralis minor muscle length was measured using a vernier caliper and scapula index, which indicated the scapular position, measured using a measuring tape. All these measurements were taken on both dominant and nondominant sides. The GIRD and total motion arc (TMA) deficit were calculated from the ROM measurements. Groups were compared using a mixed-model analysis of variance. RESULTS: There was a significant interaction between group and ABER dominance. Other variables were not seen as the interaction effect. There was a significant positive correlation between the scapula index and TMA (r = 0.47, P = .02) and a negative correlation between the scapula index and GIRD (r = -0.65, P < .01) in the dominant side of the pain group. In addition, in the nondominant side of the pain group, the scapula index and ABER were significantly correlated (r = 0.43, P = .04). CONCLUSIONS: The results of this study indicate that the scapular position is associated with the glenohumeral ROM in high school baseball players. In addition, this study demonstrated that the scapular internally rotated position was correlated with the GIRD and TMA deficit in high school baseball players who had throwing-related pain. On the other hand, the scapular externally rotated position was correlated with increased ABER, mainly in the pain-free baseball players or on the nondominant side. These results indicated that the scapular position might affect the glenohumeral rotational ROM in high school baseball players.

High-sensitivity cardiac troponin serving as a useful marker for the early recognition of relapse of isolated cardiac sarcoidosis: a case report.

Background: Isolated cardiac sarcoidosis is a relatively rare disease that is difficult to manage because of challenges in determining the progression and flare-up of cardiac lesions. Routine reduction of glucocorticoid doses may lead to treatment failure and disease relapse, which are associated with increased mortality. Case summary: Herein, we present the case of a 49-year-old woman with isolated cardiac sarcoidosis in whom high-sensitivity cardiac troponin served as a biomarker for tailoring immunosuppressive therapy. She presented with progressive dyspnoea on exertion for 2 months and had elevated levels of high-sensitivity cardiac troponin I (hs-cTnI) at presentation. A diagnosis of isolated cardiac sarcoidosis was made based on the finding of electrocardiography, echocardiography, cardiac magnetic resonance imaging, and 18F-fluorodeoxyglucose (FDG) positron emission tomography. After the introduction of glucocorticoids, the hs-cTnI concentration immediately decreased, followed by the disappearance of FDG uptake in the heart. However, 2 months after oral prednisolone was reduced to the maintenance dose, the hs-cTnI concentration began to increase gradually, and 2 months later, worsening heart failure, progression of impaired left ventricular function, and de novo accumulation of FDG in the heart were observed, confirming the relapse of cardiac sarcoidosis. Intensified glucocorticoid therapy resulted in another immediate decrease in hs-cTnI concentration and improved heart failure management. Discussion: This case highlights the potential of hs-cTnI to serve as a serum biomarker for monitoring disease activity and response to immunosuppressive therapy in patients with cardiac sarcoidosis. The hs-cTnI could be a highly sensitive and cost-effective biomarker reflecting the inflammatory status of cardiac sarcoidosis.

Effect of radiofrequency and ethanol ablation on epicardial conduction through the vein of Marshall: How to detect and manage epicardial connection across the mitral isthmus.

BACKGROUND: The vein of Marshall (VOM), which is surrounded by the Marshall bundle (MB), behaves as an epicardial connection bypassing the mitral isthmus. The influence of radiofrequency ablation and VOM ethanol infusion (VOM-EI) on epicardial MB conduction remains unclear. OBJECTIVE: The purpose of this study was to evaluate MB conduction status during mitral isthmus ablation. METHODS: Of 57 consecutive patients undergoing mitral isthmus ablation, 50 with electrode catheter cannulation into the VOM were analyzed. MB conduction was investigated by evaluating electrograms inside the VOM. Endocardial ablation was initially performed, followed by ablation inside the coronary sinus (CS), if required. Selective VOM-EI was performed if the MB potentials still exhibited early activation after radiofrequency ablation, suggesting the presence of MB connection bridging the mitral isthmus. RESULTS: VOM electrograms composed of near-field MB and far-field left atrial potentials were recorded in all patients. Solely with endocardial ablation, 33 patients (66%) achieved entire mitral isthmus block, and 43 patients (86%) achieved an epicardial MB conduction block. MB potentials exhibited early activation in the remaining 7 (14%), even after requiring CS ablation. VOM-EI then was performed. Elimination of MB potentials was verified by electrode catheter reinsertion after VOM-EI. Mitral isthmus conduction was successfully blocked during VOM-EI in 4 patients and during additional radiofrequency ablation in the remaining 3. All patients finally achieved entire mitral isthmus block. CONCLUSION: MB is effectively ablated by radiofrequency ablation. Continuous evaluation of MB conduction can reveal epicardial conduction and ablation effect. A residual MB epicardial connection is relatively rare but can be ablated by VOM-EI.

Multivariate analysis of the surface water in tropical river-estuary-sea continuums with changing land use.

The monitoring and assessment of surface water properties has been mainly conducted for freshwater rivers using multivariate analyses. The present study aimed to evaluate the effectiveness of introducing the absorption spectrum of water in order to develop a better monitoring and assessment technique for the surface waters of a river-estuary-sea continuum. Fourteen variables were measured at 17 different sites along three rivers, including estuaries and coastal sea, in Brunei Darussalam, Borneo, from August 2017 to December 2020. Among the 17 sites, freshwater streams surrounded by primary forests and coastal seawaters had the lowest ranges of the absorption coefficient at 350 nm, suspended solids, and nutrients, but had the highest range of dissolved oxygen concentration. The other sites were more or less affected by natural leaching of chromophoric dissolved organic matter (CDOM) from forests, soil runoff from agricultural lands, and wastewater discharge from urban and industrial activities. The principal component analysis (PCA) showed that four principal components were significant and explained 91% of the total variance in the data set. Four most explanatory factors were also extracted using the factor analysis (FA). In addition to the absorption spectrum, only seven basic water variables (salinity, pH, dissolved oxygen, total suspended solid, particulate organic matter, particulate inorganic matter, phosphate) were found to be necessary to assess the spatial variations in water properties at the present river-estuary-sea continuum. We conclude that it is important to include absorption spectrum data in water monitoring programs for more efficient and comprehensive assessment at land-sea interfaces.

Intuitive diagnosis of complex atrial tachycardia mechanisms using a novel histogram module of an ultra-high-resolution mapping system.

PURPOSE: The LUMIPOINT™ software module was developed to aid the physician in determining the mechanism of individual atrial tachycardias (ATs). The purpose of this study was to assess the clinical utility of the SKYLINE™ histogram that is a part of LUMIPOINT™. METHODS: This study included consecutive patients with iatrogenic sustained AT who underwent catheter ablation using conventional mapping (RHYTHMIA™). SKYLINE™ patterns were analyzed offline and classified into two types: (1) focal type (type-F) exhibiting a low-amplitude (relative activating surface area < 10%) plateau period and (2) reentrant type (type-R) showing no plateau period. How well the two patterns distinguished between focal and macroreentrant ATs as determined by conventional mapping was evaluated. RESULTS: We studied 101 iatrogenic ATs in 91 patients (female: 24, mean age: 67.3 ± 9.1 years). Activation mapping revealed 79 (78.2%) macroreentrant, 6 (5.9%) localized reentrant, and 16 (15.8%) focal ATs. Among the 72 type-R ATs, the mechanism was truly a macroreentry in 70 ATs. However, one focal AT and one localized reentrant AT displayed a type-R pattern (pseudo-reentry pattern). In the 29 type-F ATs, nine macroreentrant ATs were recognized (pseudo-focal pattern). Using SKYLINE™ type-R to differentiate macroreentrant AT from AT with centrifugal activation (focal or localized reentry), the sensitivity and specificity were 88.6% and 90.9%, respectively. Even when the SKYLINE™ type did not match the mapping-based AT mechanism, all discrepancies were electrophysiologically explicable using the SKYLINE™ histograms. CONCLUSIONS: SKYLINE™ histograms are a useful tool for the intuitive diagnosis of AT mechanisms.

Real-time visualization of the esophagus and left atrial posterior wall by intra-left atrial echocardiography.

PURPOSE: Localization of the esophagus and the left atrium (LA) posterior wall thickness (LAPWT) should be taken into account when delivering radiofrequency energy. To validate the visualization of the esophagus and analyze LAPWT by ICE advanced into the LA in patients with atrial fibrillation (AF) undergoing ablation index (AI)-guided pulmonary vein (PV) isolation. METHODS: In 73 patients (mean age, 68 ± 12; paroxysmal AF in 45), a 3-dimensional (3D) esophagus image was created with CARTO SoundstarⓇ and its location was compared with contrast esophagography saved in Carto UNIVU™. LAPWT adjacent to the esophagus was measured at 4 levels: left superior PV (LSPV), intervenous carina (IC), left inferior PV (LIPV), and LIPV bottom. A target AI value was 260 (25 W power) on the esophagus demonstrated by ICE. RESULTS: All patients had the esophagus posterior to the left PV antrum. Creating a 3D esophagus and measurement of LAPWT with ICE was done without any complications. ICE esophagus image was completely overlapped with contrast esophagography. LAPWT (mm) was 2.8 (interquartile range, 2.5-3.2), 2.2 (1.9-2.5), 1.9 (1.8-2.1), and 2.1 (1.9-2.4) for LSPV, IC, LIPV, and LIPV bottom, respectively, while LA roof thickness was 3.2 (2.9-3.6) (P < 0.0001 by ANOVA). No residual conduction gap on the esophagus after the first circumferential PV isolation was found in 64 of 73 (88%) patients. CONCLUSIONS: ICE inserted into the LA can reliably locate and display the esophagus and its relationship to the LA. LAPWT was the thinnest at the LIPV level. AI-guided ablation targeting at AI value 260 on the esophagus seemed to be effective.

Acute effects of doorway stretch on the glenohumeral rotational range of motion and scapular position in high-school baseball players.

BACKGROUND: Pectoralis minor tightness has been thought to affect the scapular position. Despite the wide implementation of doorway stretch in clinical practice owing to its apparent effectiveness in stretching the pectoralis minor, limited studies have investigated its influence on the glenohumeral rotational range of motion (ROM). This study aimed to examine the acute effects of doorway stretch on the glenohumeral rotational ROM and the correlation between the scapular position and ROM. MATERIALS AND METHODS: In total, 34 male high-school baseball players participated in this study. Outcomes included the pectoralis minor muscle length, glenohumeral rotational ROM, and scapular position. The distance between the sternocostal joint of rib 4 and the coracoid process was measured as the pectoralis minor length. Internal and external rotation ROM with the shoulder abducted at 90° were measured. The scapular position was defined by the following two measurements: the distance between the surface and the posterolateral corner of the acromion as well as the scapular index. The participants performed doorway stretch by abducting and externally rotating the shoulder at 90° and flexing the elbow at 90°. The outcomes were compared before and after stretching. Furthermore, the correlation between these changes was investigated. RESULTS: Pectoralis minor muscle length and glenohumeral internal rotation ROM was significantly higher after stretching than before, and the scapular position also significantly changed (P < .01 for both). A moderate correlation was found between the degree of change in the glenohumeral internal rotational ROM and scapular position (r = 0.44, P < .01). DISCUSSION: Our results indicated that doorway stretch significantly increased the pectoralis minor muscle length and glenohumeral internal rotation ROM and significantly altered the scapular position. Furthermore, a significant correlation between the degree of change in the scapular position and glenohumeral internal rotation ROM was observed. These results suggest that doorway stretch could be beneficial for improving the scapular position and glenohumeral internal rotation ROM, which are considered the cause of throwing injuries. Furthermore, the glenohumeral ROM may be affected by the scapular position.

Ablation Index-Guided High-Power Radiofrequency Application Shortens the Procedure Time With Similar Outcomes to Conventional Power Application in Atrial Fibrillation Ablation.

Background: The impact of high-power radiofrequency (RF) application in ablation index (AI)-guided atrial fibrillation (AF) ablation has not been elucidated. Methods and Results: We investigated 1,333 patients undergoing first AF ablation (median age 68 years; interquartile range [IQR] 61-73 years). The first 301 patients underwent AI-guided conventional power RF application (CP group), whereas the following 1,032 patients underwent high-power RF application (HP group). The minimum AI target values were 400, 360, and 260 at the left atrial anterior wall, posterior wall, and esophagus, respectively. RF power in the CP group was 30-40, 20-25, and 20 W at the anterior wall, posterior wall, and esophagus, respectively, compared with 50, 40, and 25, respectively, in the HP group. Procedure time was shorter in the HP than CP group (median 153 [IQR 129-190] vs. 180 (IQR 152-229) min; P<0.0001). The percentage of first-pass pulmonary vein isolation (69% vs. 73%; P=0.07) and all procedure-related complications (2.0% vs. 3.4%; P=0.19) was similar. Kaplan-Meier analysis showed similar recurrence-free survival (RFS) for all AF types. Respective 1-year RFS in the CP and HP groups was 82% and 87% in paroxysmal AF, 78% and 82% in persistent AF, and 59% and 58% in long-standing persistent AF. Conclusions: In AI-guided AF ablation, high-power RF application shortens the procedure time without increasing complications and with similar outcomes.

A prospective multicenter study of direct comparison of feasibility and safety of pulmonary vein isolation using the minimally interrupted apixaban between second-generation cryoballoon and radiofrequency ablation of paroxysmal atrial fibrillation: J-HIT apixaban.

BACKGROUND: The feasibility and safety of pulmonary vein isolation (PVI) using cryoballoon (CB) for paroxysmal atrial fibrillation (PAF) with minimally interrupted apixaban has not fully explored. METHODS: In this multicenter, randomized prospective study, we enrolled patients with PAF undergoing CB or radiofrequency (RF) ablation with interrupted (holding 1 dose) apixaban. The primary composite end point consisted of bleeding events, including pericardial effusion and major bleeding requiring blood transfusion, or thromboembolic events at 4 weeks after ablation; secondary end points included early recurrence of AF and procedural duration. RESULTS: A total of 250 patients underwent PVI (125 assigned to the RF ablation and 125 assigned to the CB ablation). The primary end point occurred in 1 patient in the CB ablation group (0.8%; 90% confidence interval [CI], 0.04 to 3.70) and 3 patients in the RF group (2.4%, P = .622; risk ratio, 0333; 90% CI, 0.05 to 2.20). All events were pericardial effusion, all of whom recovered after pericardiocentesis. Early recurrence of AF occurred in 4 patients (3.2%) in the RF group and in 6 patients (4.8%) in the CB group (P = .749). The procedural duration was shorter in the CB group than that in the RF group (136.5 ± 39.9 vs 179.5 ± 44.8 min, P < .001). CONCLUSION: CB ablation with minimally interrupted apixaban was feasible and safe in patients with PAF undergoing PVI, which was equivalent to RF ablation.

Organic Carbon and Nitrogen Isoscapes of Reef Corals and Algal Symbionts: Relative Influences of Environmental Gradients and Heterotrophy.

The elemental (C/N) and stable isotopic (δ13C, δ15N) compositions and compound-specific δ15N values of amino acids (δ15NAA) were evaluated for coral holobionts as diagnostic tools to detect spatiotemporal environmental heterogeneity and its effects on coral health. Hermatypic coral samples of eight species were collected at 12 reef sites with differing levels of pollution stress. The C/N ratios, δ13C values, and δ15N values of coral tissues and endosymbiotic algae were determined for 193 coral holobionts, and the amino acid composition and δ15NAA values of selected samples were analyzed. δ15N values were influenced most by pollution stress, while C/N ratios and δ13C values depended most strongly on species. The results imply that δ13C and δ15N values are useful indicators for distinguishing the ecological niches of sympatric coral species based on microhabitat preference and resource selectivity. Using δ15NAA values, the trophic level (TL) of the examined coral samples was estimated to be 0.71 to 1.53, i.e., purely autotrophic to partially heterotrophic. Significant portions of the variation in bulk δ15N and δ13C values could be explained by the influence of heterotrophy. The TL of symbionts covaried with that of their hosts, implying that amino acids acquired through host heterotrophy are translocated to symbionts. Dependence on heterotrophy was stronger at polluted sites, indicating that the ecological role of corals changes in response to eutrophication.

Responses of branching reef corals Acropora digitifera and Montipora digitata to elevated temperature and pCO2.

Anthropogenic emission of CO2 into the atmosphere has been increasing exponentially, causing ocean acidification (OA) and ocean warming (OW). The "business-as-usual" scenario predicts that the atmospheric concentration of CO2 may exceed 1,000 µatm and seawater temperature may increase by up to 3 °C by the end of the 21st century. Increases in OA and OW may negatively affect the growth and survival of reef corals. In the present study, we separately examined the effects of OW and OA on the corals Acropora digitifera and Montipora digitata, which are dominant coral species occurring along the Ryukyu Archipelago, Japan, at three temperatures (28 °C, 30 °C, and 32 °C) and following four pCO2 treatments (400, 600, 800, and 1,000 µatm) in aquarium experiments. In the OW experiment, the calcification rate (p = 0.02), endosymbiont density, and maximum photosynthetic efficiency (Fv/Fm) (both p < 0.0001) decreased significantly at the highest temperature (32 °C) compared to those at the lower temperatures (28 °C and 30 °C) in both species. In the OA experiment, the calcification rate decreased significantly as pCO2 increased (p < 0.0001), whereas endosymbiont density, chlorophyll content, and Fv/Fm were not affected. The calcification rate of A. digitifera showed greater decreases from 30 °C to 32 °C than that of M. digitata. The calcification of the two species responded differently to OW and OA. These results suggest that A. digitifera is more sensitive to OW than M. digitata, whereas M. digitata is more sensitive to OA. Thus, differences in the sensitivity of the two coral species to OW and OA might be attributed to differences in the endosymbiont species and high calcification rates, respectively.

High-power application is associated with shorter procedure time and higher rate of first-pass pulmonary vein isolation in ablation index-guided atrial fibrillation ablation.

BACKGROUNDS: Ablation index (AI) is useful to complete circumferential pulmonary vein isolation (CPVI) for atrial fibrillation (AF), but the role of radiofrequency power in AI-guided CPVI remains to be elucidated. METHODS: We investigated 60 patients with AF undergoing AI-guided CPVI (mean age, 66 ± 9 years; nonparoxysmal AF in 16). The first 40 patients were randomly assigned to low-power (LP; n = 20) and medium-power (MP; n = 20) groups and the following 20 patients to high-power (HP). In LP, radiofrequency (RF) application was done at 30 W at the anterior and 20 W at the posterior left atrial (LA) wall, while in MP, it was at 40 W at the anterior and 30 W at the posterior LA wall. In HP, 50 W was applied at the anterior, 40 W at posterior LA wall and 30 W on the esophagus. At each ablation point, target AI was 400 at the anterior, 360 at the posterior LA wall, and 260 on the esophagus. RESULTS: The time to complete both-side CPVI was shortest in HP (median, 40 minutes, interquartile range [IQR], 28-63) followed by MP (58 [49-83] minutes, P = .008 vs HP) and LP (84 [72-93] minutes, P = .002 vs MP). Higher RF power application significantly increased first-pass isolation rate (55% in LP, 80% in MP and 85% in HP, P = .002) and decreased LA-PV reconnection rate (10% in LP, 8% in MP, and 0% in HP, P = .03). CONCLUSION: In AI-guided PVI, the HP RF application can shorten the time to complete PVI with a high rate of first-pass isolation and a low rate of LA-PV reconnection.

Simple and novel technique to confirm complete mitral isthmus block.

BACKGROUND: Differential pacing technique to confirm mitral isthmus (MI) block is sometimes challenging due to destroyed tissues after extensive ablation. The purpose of this study is to set an endpoint of MI ablation using conduction time around the mitral annulus (MA). METHODS: Forty-five consecutive patients with persistent atrial fibrillation who received MI linear ablation were included. The geometry and activation times of the left atrium around the MA were collected using a multipolar catheter before ablation. During coronary sinus (CS) pacing, the time between the stimulus and the wave-front collision at the opposite side of the MA (defined as T/2) was calculated, and the doubled value was defined as the estimated perimitral conduction time (E-PMCT). The endpoint for complete MI block was when the stimulus (at distal CS) minus the maximal delayed potential (St-MDP) on the MI interval reached the E-PMCT. RESULTS: St-MDP reached E-PMCT during MI ablation in 44/45 patients. Among these 44 patients, differential pacing revealed bidirectional block in 39/44 (88.6%), whereas in 5/44 (11.4%), the differential pacing was not possible because of the loss of capture of local potentials due to extensive applications around the linear line. In one patient, the St-MDP did not reach E-PMCT (E-PMCT: 148 ms, St-MDP :130 ms) and differential pacing revealed no MI block. E-PMCT values (median 176 ms) correlated strongly with St-MDP (median 185 ms, P < 0.0001, R = 0.98). CONCLUSIONS: Although E-PMCT differs between individuals, the value is significantly correlated with the St-MDP. This technique may be useful in providing an individual endpoint of MI ablation as an alternative to differential pacing.