Direct flow, which is the portion of LV volume that passes directly from inflow to outflow in a single cycle. We hypothesize that impaired LV flow patterns and energetics will be found immediately after cardioversion during atrial stunning, and that those parameters will improve as atrial function returns.Atrial fibrillation (AF) is a prevalent cause of cardiovascular morbidity, including thromboembolism and heart failure. Left ventricular dysfunction (LVD) detected in AF patients may be either precursor or consequence of the arrythmia. Successful cardioversion of chronic AF is often followed by a transient period of left atrial (LA) stunning, where depressed mechanical atrial contraction persists despite reinstitution of sinus rhythm. To determine if AF-associated LVD would improve with resolution of LA dysfunction, AF patients were examined immediately and 4 weeks after cardioversion to sinus rhythm. 4D flow cardiovascular magnetic resonance (CMR) assesses ventricular function according to the volumes and energetics of functional components of the LV volume. Previously, described 4D CMR markers of LVD include decreased volume and end-diastolic kinetic energy (KE) of the Ten patients with a history of AF underwent CMR 2–3 h (Time-1) and 4 weeks (Time-2), following electrical cardioversion to sinus rhythm. 4D phase-contrast velocity data and morphological images were acquired at a 3T CMR system. Using a previously evaluated method, pathlines were emitted from the LV end diastolic volume (LVEDV) and traced forward and backward in time until end-systole. The LVEDV was automatically separated into four functional flow components whose volume and KE were calculated.P = 0.001), indicating recovery of LA mechanical function. LVEF increased between Time-1 and Time-2 (P = 0.003); LVEDVI did not change (P = 0.319). Over that interval, the ratios of Direct flow/LVEDV volume and KE increased , while the ratios of Residual volume/LVEDV volume and KE decreased .Left atrial fractional area change increased over the follow-up period (Post-cardioversion recovery of LA function was associated with improvements in conventional and 4D CMR markers of LV function. Flow-specific measures demonstrate the negative but potentially reversible impact of LA dysfunction on volume and energetic aspects of LV function. Atrial fibrillation (AF) affects more than 3% of the population . The conSeveral mechanisms underlying LVD in AF patients have been proposed, including sustained tachycardia, chronic heart rate irregularity, the loss of organized atrial contraction , and theDirect flow component) reflect left atrial (LA)-ventricular coupling, and decreases in them have been proven to be markers of LVD in idiopathic dilated and ischemic cardiomyopathy with or without left bundle branch block  of functional components of the left ventricular (LV) volume. The volume and KE at end-diastole of the portion of LV inflow which passes directly to outflow  and all patients gave written informed consent prior to participation in the study. The patients were recruited from the department of cardiology, Linköping University Hospital, Sweden. Patients with persistent AF lasting more than 3 weeks prior to cardioversion and scheduled for elective electrical cardioversion were included. Exclusion criteria were: (1) uncontrolled hypertension (>160/95 mmHg), (2) LV ejection fraction <40%, (3) age >80 years, (4) previous ablation or heart surgery, (5) more than mild to moderate valvular disorder of the aortic or mitral valve, (6) more than moderate dilatation of the left ventricle , (7) contraindications for MRI-examination, and (8) recurrent AF occurring within the 4 weeks following the initial cardioversion that was not re-converted to sinus rhythm within 48 h. Eight patients were excluded, four due to recurrence of AF and four due to inadequate data quality.3. Parallel imaging (SENSE) with a reduction factor of three was used to decrease the scan time. In order to further reduce scan time, two rows of k-space, where acquired for each scan segment per cardiac cycle (k-space segmentation factor = 2), resulting in an acquired temporal resolution of 40.8 ms. After the acquisition, the 4D flow data were reconstructed into 40 time frames on the scanner using a temporal sliding window with individual stretching of each RR-interval. Data were corrected for concomitant gradient field effects on the scanner.All 18 patients underwent a examination on a clinical 3 T CMR system  two to three h after the cardioversion (Time-1). Four weeks after the cardioversion (Time-2), a second CMR examination was performed on 14 patients. During each CMR examination, time-resolved, three-directional velocity data (4D flow MRI) in a volume encompassing the LA and LV were acquired along with morphological 2D bSSFP images in three standard long axis (LAx) orientations  and two stacks of short axis (SAx). One SAx image stack was acquired prior to the 4D flow scan, and the other after the 4D flow scan. The 4D flow data were acquired during free-breathing using respiratory gating, and with interleaved three-directional flow encoding and retrospective, vector cardiogram controlled cardiac gating, thus covering the whole cardiac cycle. The arrhythmia rejection mode was activated in order to exclude possible irregular cardiac cycles. General acquisition parameters for the 4D flow data were: VENC: 120 cm/s; Repetition Time, 5.1 ms; Echo Time, 3 ms; Flip Angle, 5°. The spatial resolution was 2.8 × 2.8 × 2.8 mm2 and the LAx images 0.83 × 0.83 mm2.The morphological bSSFP images were acquired using the following settings: Echo Time, 1.4 ms; Repetition Time, 2.8 ms, Flip Angle, 45°. The bSSFP images were reconstructed into 30 time frames with a slice thickness of 8 mm. SAx images were reconstructed with a pixel size of 0.9 × 0.9 mmThe “Linköping 4D Flow Tool” was used to post–process and analyze the 4D flow MRI data . In thisThe LV flow components were analyzed using a previously evaluated method . The LV 3. To measure pathlines’ trajectories during diastole, pathlines were traced backward in time in the reversed velocity field, which is like asking each pathline: Where did you come from? To measure trajectories during systole the pathlines were traced forward, which is like asking: Where are you going? By merging these backward and forward trajectories, the full EDV could be traced throughout the cardiac cycle from onset diastole to end systole. The ES segmentation was used to determine the pathlines’ location inside (retained) or outside (ejected) the LV at end-systole. All pathlines were then divided into four different components : Pathlines that enter and leave the LV during the analyzed cardiac cycle.Retained Inflow (RI): Pathlines that enter the LV during diastole of the analyzed cardiac cycle and remain in the LV during the subsequent systole.Delayed Ejection Flow (DEF): Pathlines that start within the LV and leave during the systole of the analyzed cardiac cycle.Residual Volume (RV): Pathlines that start within the LV and remain within the LV at the end of systole.The volume and KE were calculated from the particle traces assigned to each flow component, as previously described .Conventional portions of LV volume including LV inflow, LV stroke volume and non-ejected LV volume were calculated from the flow-based components as follows:Direct flow + Retained inflowLV inflow = Direct flow + Delayed ejection flowStroke volume = Retained inflow + Residual volumeNon-ejected volume = The total LV inflow was calculated for the entire diastolic period, and late diastolic inflow was calculated over the late diastolic period.Pathlines from all the subjects were visualized in EnSight . The overall pattern of flow within the LV throughout diastole, including the four flow components, was assessed by visual inspection by two investigators in consensus. The investigators had 1 and 20 years of experience in cardiac imaging, respectively.In order to ascertain the quality of the acquired data, the differences in LV inflow and outflow were assessed for each study. Patients were excluded if the LV inflow versus outflow discrepancy was more than 15%. Flow pathlines were visualized in EnSight  and inspected for aberrant traces leaving the cardiac confines which would indicate impaired data quality.The LA fractional area change (FAC) reflects the extent of atrial contraction. The largest and smallest LA areas were identified and measured twice from the 4-chamber long axis slice using Segment. The mean of the two measurements was used to calculate the LA FAC:LA FAC =  × 100/largest LA areat-tests. Statistical significance was set at p < 0.05. Since the number of included patients were rather few, we also performed a non-parametric analysis (Wilcoxon signed-rank test). This analysis revealed the same pattern of significance (data not shown) All statistical comparisons were made in Statistica .To test the normal distribution assumption of the samples the Kolmogorov–Smirnov test was used. Data are presented as mean ± 1 standard deviation (SD). Statistical comparisons were made with paired students p = 0.003). All patients were receiving beta-blocker therapy; all received angiotensin converting enzyme inhibitor/angiotensin II receptor blocker and/or calcium antagonists. The medication remained the same between Time-1 and -2. In terms of the previous burden of AF, seven out of ten patients had only experienced one episode of AF and the remaining three patients had experienced 2-3 episodes. The duration of the last AF episode was approximately one month in five of the patients and 2-3 months in the remaining five patients. For a more thorough description regarding clinical background data, please see Demographic and clinical patient data are provided in p = 0.081), whereas the minimum area decreased over that interval , whereas the LV end systolic volume index decreased (p = 0.011) (p = 0.138).The LVEDVI did not change significantly from Time-1 to Time-2 (= 0.011) . In comp= 0.011) . The carp < 0.001). On an individual basis, the LVEF improved in all subjects over that interval , representing 5 ± 4%  of the inflow volume.Direct flow volume and KE ratios increased from Time-1 to Time-2 . The improvement in atrial contraction after cardioversion was reflected in the increase of the late diastolic contribution of volume and KE to the total inflow from Time-1 to Time-2 . The non-ejected LV volume decreased in volume but increased in KE at ED from Time-1 to Time-2 (p = 0.006 and p = 0.049).Flow components were combined to evaluate the Stroke volume and the non-ejected volume. The volume and KE at ED of the stroke volume increased from Time-1 to Time-2  in patients with mild to moderate LVD. The Time-2 Direct flow volume ratio (37%) is close to the values reported in subjects with normal cardiac function in previous studies .LK, AB, and CC conceived and designed the study and edited the manuscript critically. LK and HE recruited the patients. LK, HE, TE, and CC were involved in data collection. HE and CC analyzed the data. HE, AB, and CC interpreted the results and prepared the figures. HE drafted the manuscript. TE revised the manuscript. All authors read, approved the final manuscript and agreed to be accountable for all aspects of the work in ensuring that questions related to the accuracy of integrity of any part of the work are appropriately investigated and resolved.The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.


Melospiza melodia melodia) from the same partially migratory breeding population to different photoperiodic schedules associated with a 1,300‐km difference in overwintering location. One group remained on the natural photoperiodic schedule of the breeding site (resident group) while the other group experienced a nonbreeding photoperiod that mimicked a southern migration in the fall followed by a northern migration back to the breeding site in the spring (migratory group). We compared song output between the two groups in three different stages . Little singing occurred during nonbreeding stage sample dates  for the resident group, and no singing occurred for the migrant group. During the prebreeding stage , significantly more singing occurred in the resident group than in the migrant group. During the breeding stage , after a simulated migration for the migrants, song output was similar in both groups. These results suggest that within‐population variation in wintering latitude may contribute to variation in seasonal changes in singing behavior, which may covary with readiness to breed. Studies utilizing confirmed migrants and residents, rather than merely simulated migrants and residents, are also needed to better understand these processes.Migratory bird populations frequently consist of individuals that overwinter variable distances from the breeding site. Seasonal changes in photoperiod, which varies with latitude, underlie seasonal changes in singing frequency in birds. Therefore, migratory populations that consist of individuals that overwinter at different latitudes with large overwintering ranges could experience within‐population variation in seasonal production of song. To test the influence of overwintering latitude on intrapopulation variance in song production in the spring, we subjected two groups of Eastern Song Sparrows  that we subjected to natural photoperiods of Tampa, Florida, and Bloomington, Indiana, respectively. We found that the residents sang more during the prebreeding stage, but after a simulated spring migration, song output in the two groups was the same. However, no study that we are aware of has investigated the singing behavior of individuals of a species simultaneously at a location where that species occurs year‐round and at a location where that species solely overwinters. Lymburner, Kelly, Hobson, MacDougall‐Shackleton, and MacDougall‐Shackleton's study  compare with respect to singing behavior on the nonbreeding grounds when allopatric and then later on the breeding grounds when sympatric. Further, a comparison of singing behavior in both groups could be correlated with the ability of the focal species to respond to changes in climate. For example, species with greater variance in timing of breeding and associated behaviors will likely be better able to withstand environmental change . Several different subspecies of Song Sparrows are distributed throughout much of North America, particularly in riparian habitats, in both urban and rural environments. Song Sparrows breed as far north as 58°N and as far south as 19°N. Throughout most of their range north of 43°N, breeding individuals are migratory and overwinter to the south, just as individuals overwintering south of 33°N are migratory and breed to the north. Between 33°N and 43°N, some Eastern Song Sparrows are year‐round residents and some are migrants. Thus, during the nonbreeding season, Eastern Song Sparrows from the same breeding population may simultaneously experience a variety of photoperiods due to migration.We chose to address these needs and to study the partially migratory Eastern Song Sparrow . We sexed each bird as male in the field by identifying the presence of a cloacal protuberance and by the bird's singing behavior. All birds were lured into mist nets with recordings of Song Sparrow song and then banded with a USGS metal band. A small quantity of blood (<50 µl) was collected from the brachial vein by venipuncture for molecular sex determination. We used quality of streaking of the breast and eye color to determine that our captured birds had already surpassed their hatch‐year Pyle, .2.2We randomly assigned all 24 birds to one of two, indoor aviaries maintained at 21°C, such that there were 12 birds in each aviary. The aviaries were similar in size (3.9 × 3.5 × 2.5 m and 3.5 × 3.1 × 2.5 m). Due to their year‐round territoriality, male Song Sparrows should be housed individually to avoid fighting  would take to travel 1,300 km, according to one estimate  mounted on a tripod to record singing behavior in both aviaries every week between 1 November 2018 and 4 April 2019, with a recording session simultaneously occurring in both aviaries, on two  days per week. We manually turned on cameras 10–15 min after lights were automatically turned on in a given aviary at “sunrise.” The camera recorded audio and video until memory ran out, which generally occurred after about 3.5 hr of operation. The movements of singing birds were sufficient to match individual birds and their song types, despite multiple birds sometimes singing simultaneously. To ensure that the birds in each aviary experienced auditory stimulus, every recording session we exposed the birds to playback of Song Sparrow song. In both aviaries, we placed a playback system  which was started each recording session at the same time that the camera was turned on. This system broadcast between 30 s and 1 min 15 s of song approximately every 30 min (same recording for both aviaries), beginning 5 min after the camera was turned on, and had a duration of 2 hr. The recordings consisted of songs from 3 Song Sparrows chosen randomly. The songs were recorded 6 km from the site that we captured the birds for the current experiment.We determined song type repertoires for each individual so that instances of song that we recorded could be attributed to individuals, even when we did not see them singing on camera. Cassidy  found thWe used Audacity (version 2.2.2) to generate spectrograms for each song type, using recordings extracted from the video cameras. Song Sparrows in at least one population do not alter their song repertoire after the first spring of their second calendar year of life  and based on the observations of Nice , who obsFor each 30‐min period analyzed (each began 30 min after the camera was turned on), we first generated spectrograms for all song types uttered and counted the number of times each song type was uttered. Then, we assigned the song types to individuals based upon the song types identified for individuals during the camera recording sessions. This allowed us to acquire a song count value for each individual. Though individuals did share some song types, subtle differences in song structure were generally sufficient to assign even shared song types to individuals, as in Beecher et al. . When we2.5We used generalized linear mixed models to analyze effects of resident status, breeding stage, and the interaction between resident status and breeding stage (fixed effects) on song output , with individual identity as a random factor. Prior to the start of the experiment, one resident bird was excluded from sampling because its behavior appeared to be affected by an infection. Three additional birds were excluded from our analyses because they died in captivity from unknown illnesses, leaving 10 birds in each treatment. We only included the prebreeding and breeding stages in the analysis because the majority of birds in both treatments did not sing during the nonbreeding stage.p = .05. All measures of variability are indicated by “±” standard error. Figures were made using R 3.6.0 , and two‐tailed tests were used for all analyses, with a significance level of 2.6Once per week from February to March, we collected blood and measured fat from all birds in both aviaries on a day in which camera recordings did not take place. We assume that this affected both aviaries equally.USFWS permit MB94788C‐0 approved collection of Song Sparrows from the wild, as did Indiana DNR permit 18‐049.Captive protocols were approved by the Indiana University Institutional Animal Care and Use Committee # 18‐018.3For both migrants and residents, there was little song output during the nonbreeding stage . During the prebreeding stage in both treatments, most birds sang and by the breeding stage all birds sang Table .F1, 18 = 2.07, p = .167), though did tend to vary when breeding stage was considered . There was an interaction between breeding stage and treatment , with migrants and residents differing in song output during the prebreeding stage and not the breeding stage  Bloomington days had surpassed Tampa photoperiod length  on the nonbreeding grounds.Overall, the pattern that we observed is consistent with the “rank advantage hypothesis”  confined together could affect song output (Boseret, Carere, Ball, & Balthazart, In order to build upon our incipient understanding of how the singing behavior of songbirds varies in the nonbreeding and breeding range, laboratory or field studies which better account for real‐world variables are required. Such studies could help to elucidate functional advantages or disadvantages of differential frequency and onset of singing behavior. From a conservation perspective, understanding the degree to which migratory songbirds vary in timing of breeding, for which song could possibly serve as a proxy, may prove useful.We do not have any competing interests.DB caught the birds, designed the experiment, matched songs and singers, analyzed data, and wrote the manuscript. AF designed the experiment, analyzed the data, and helped revise the manuscript. CM matched songs and singers and approved the final manuscript. Click here for additional data file.


Megaptera novaeangliae) song in the northeast Pacific from three years of continuous recordings off central California . Song is prevalent in this feeding and migratory habitat, spanning nine months of the year (September–May), peaking in winter (November–January), and reaching a maximum of 86% temporal coverage (during November 2017). From the rise of song in fall through the end of peak occurrence in winter, song length increases significantly from month to month. The seasonal peak in song coincides with the seasonal trough in day length and sighting-based evidence of whales leaving Monterey Bay, consistent with seasonal migration. During the seasonal song peak, diel variation shows maximum occurrence at night (69% of the time), decreasing during dawn and dusk (52%), and further decreasing with increasing solar elevation during the day, reaching a minimum near solar noon (30%). Song occurrence increased 44% and 55% between successive years. Sighting data within the acoustic detection range of the hydrophone indicate that variation in local population density was an unlikely cause of this large interannual variation. Hydrographic data and modeling of acoustic transmission indicate that changes in neither habitat occupancy nor acoustic transmission were probable causes. Conversely, the positive interannual trend in song paralleled major ecosystem variations, including similarly large positive trends in wind-driven upwelling, primary productivity, and krill abundance. Further, the lowest song occurrence during the first year coincided with anomalously warm ocean temperatures and an extremely toxic harmful algal bloom that affected whales and other marine mammals in the region. These major ecosystem variations may have influenced the health and behavior of humpback whales during the study period.This study examines the occurrence of humpback whale ( Since first being characterized as song nearly a half century ago , the cycEarly interpretations that humpback song occurs only in breeding habitats have yielded to a growing body of observations of humpback song occurring in feeding habitats –19 and dThe study region is the Monterey Bay National Marine Sanctuary (MBNMS), in the central California Current System CCS; . This reFavorable foraging habitat for baleen whales in the CCS results ultimately from high levels of primary productivity caused by wind-driven upwelling of nutrient-rich water into the euphotic zone ,33. The Submarine canyons are particularly important foraging hotspots for krill in the CCS . MontereThe overall aim of this study is to understand the occurrence of humpback whale song in a biologically rich feeding habitat that supports relatively dense populations of this whale species. Beyond establishing a foundational description of song occurrence in this ecologically important region, this study aims to examine ecosystem variations that may affect humpback whale foraging ecology, and therefore also song occurrence.The study approach begins with detection of humpback whale song from manual analysis of spectrograms, derived from three years of passive acoustic sensing data. Song occurrence is characterized at diel, seasonal, and interannual time scales. At the seasonal and interannual time scales, frequently acquired data from whale watching vessels serve as a proxy for local whale abundance, enabling comparison of song occurrence with statistics of humpback whale sightings in Monterey Bay. The sighting area comprises a portion of the geographic domain for which acoustic modeling defines detectability of humpback whale song at the hydrophone location. At the interannual time scale, ecosystem monitoring data enable characterization of biological factors of importance to humpback whale ecology, which may influence singing behavior. These factors include primary productivity, exposure to a neurotoxic algal compound, and forage species composition and abundance. Hydrographic data and modeling of acoustic transmission loss are applied to consider whether a specific change in geographic patterns of whale habitat occupancy, or changes in acoustic transmission, during an anomalously warm year would have altered song detection at the recording site.Lucy software for shore-side recording. In this study we examine the first three full years of recordings, acquired between 1 August 2015 and 31 July 2018. Temporary network outages in the cabled observatory resulted in 94% temporal coverage during the three years.The acoustic recordings for this study are part of a recently established passive acoustic monitoring project . RecordiThe basis for analysis of humpback song was power spectral density (PSD) computation using the Long-Term Spectral Average (LTSA ), adaptest and 99th percentiles of PSD to maximize visual contrast. (3) The frequency axis of the spectrogram was log-scaled for greater detail in the frequency range where most humpback song energy occurs  Spectrogram representations from daily to hourly resolution were simultaneously examined to integrate visual information from longer recording periods covering song sessions with high-resolution detail of song structure. 2) Color scaling for spectrograms at all temporal scales was adaptively constrained to the 1y occurs . Song wa Color scy occurs . Song prAnalyses of song occurrence at all time scales–diel, monthly, and interannual–normalized song occurrence to the corresponding total recording time. Seasonal variation of song presence was examined for all years separately and as a monthly climatology based on all three years. Because song was absent in summer and peaked in winter, the reference year for the interannual analysis extended from 1 August of one year to 31 July of the next. Diel analysis was based on solar elevation: day > 0°, night < -12°, and dusk/dawn between 0 and -12° . Solar eUsing the song presence data extracted in Stage 1, all periods of song were re-examined to quantify the length of individual songs and examine seasonal variation in song length. Consistent with published recommendations , the criPSD) is a better measure of a song profile  the source domain for our recordings of humpback song, and (2) the potential influence of variation in habitat occupancy on interannual variation in song detection. To define the frequency at which to model acoustic transmission, a subset of 429 individual humpback songs was selected for analysis. Selection required (1) signal strength sufficient to accurately represent song frequency content, i.e. avoiding faint song signal from distant whales, and (2) absence of extraneous sound sources that would contaminate analysis of song frequency content. For each song a high-resolution  LTSA was computed, and for each LTSA of a full song  the freq profile . It prov modeled .Acoustic transmission loss at 350 Hz was calculated from a wave-theory parabolic equation model that accounts for absorption in both the water column and the bottom, scattering in the water column and at the surface and bottom, geometric spreading , refraction, and diffraction . SpecifiTo interpret temporal variations in humpback song detection in relation to visual sightings, this study used sighting data from commercial whale watch operations . The primary advantages of these data are frequent sampling, with visual surveys averaging 326 ± 21 days per year during the period of this study, and consistent coverage of an area near the hydrophone  sea surface temperature (SST) monthly anomaly, 2002 through 2018, produced by NASA Jet Propulsion Laboratory and accessed through the NOAA ERDDAP server . In situPseudo‐nitzschia and can cause illness, heart and brain damage, reproductive failure, and mortality in marine mammals, including baleen whales , a, aSebast mordax) , respect mordax) , we quan mordax) ,69 (loca mordax) ,68. Fora mordax) .In examining ecosystem variations in relation to interannual changes in song occurrence, leading temporal lags are appropriate because ecosystem conditions preceding the annual  rise of singing behavior could influence whale population dynamics, foraging ecology, and behavior. Beginning with forcing of primary productivity by wind-driven upwelling, we quantify cumulative upwelling between the annual onset in spring through the end of the calendar year. For the three winters examined, strong downwelling caused by winter storms consistently ended by March. Therefore, a consistent measure of cumulative upwelling spanned March through December of each year. This same annual period was used for mean sea level in the CCS, spatially and temporally integrated primary productivity in the Monterey Bay region, and particulate domoic acid (pDA) concentrations. For pDA we quantify the annual temporal span of detection, maximum concentrations, and a potential exposure metric integrated annually by summing the product of each concentration measurement and the time period it represents (1 week). Forage data are from spring/summer of each year and provide an indicator of the overall condition of forage species populations within the central CCS . To descThe region around the hydrophone from which humpback song would be detectable under different levels of background noise is characterized from received level for a sound source having a frequency 350 Hz;  and sourThe three-year record of humpback song detection shows large seasonal and interannual variations . Like the CCS, physical distinction of the HCS caused by coastal upwelling is evident in the cooling gradient between the subtropical gyre and the eastern margin , and it Seasonal increase in the length of song sessions has been reported from analysis of recordings from the northwest Atlantic . To our 2 = 0.99). Our results on diel variation are consistent with those from the study in the HCS [As described in the methods, it is appropriate to constrain examination of diel variation to the time of year when song is prevalent. During the annual peak in song occurrence, November through January , diel va the HCS . In that the HCS ,75. Alte the HCS . Assumin the HCS .Interannual variation in humpback song occurrence was marked by 44% and 55% increases between consecutive years . BetweenConsideration of all hypotheses for the strong interannual trend in song occurrence requires the context of interannual variations in ecosystem conditions. The first year of recording coincided with the highest sea level anomalies (SLA) in the CCS in the last 25 years Y1 in . While SThe first hypothesis for causality of the positive interannual trend in song is a positive trend in the local abundance of singing whales. Our sighting data from southern Monterey Bay are within the domain of MARS acoustic detection of humpback song . AlthougThe second hypothesis is that interannual variation in song detection was influenced by changes in the geographic distribution of singing whales in relation to anomalous habitat conditions . A previ-4, respectively. The similarity in the depth and magnitude of pycnocline gradients across years indicates that hydrographic variation was unlikely to have influenced interannual variation in song detection at MARS.The third hypothesis is that changes in hydrography during this highly anomalous period  may haveExtensive observations show major ecosystem variations relevant to humpback whale ecology. Further, these variations exhibit trends consistent with the observed trend in song occurrence. The trend of integrated primary productivity (IPP) in the Monterey Bay region closely parallels that of song occurrence . IPP incConsistent with the increasing trend in primary productivity, krill transitioned from a strong negative anomaly in the first year, to near normal in the second year, to a strong positive anomaly in the third year . Adult aBeyond the magnitude of primary productivity, a potentially influential factor is the extent to which primary productivity generates algal toxins that can affect marine mammal health and behavior. Our first year of recording coincided with a severe toxic algal bloom. Detection of the toxin, domoic acid (DA), in marine mammals—including whales, dolphins, porpoises, seals, and sea lions—spanned the largest geographic extent ever recorded . ConcentThis study extends the growing body of observations showing occurrence of humpback song in feeding and migratory habitats. In the northeast Pacific, the Monterey Bay region is important feeding and migratory habitat for humpback whales. The abundance of humpback whales off the U.S. West Coast has increased from about 900 individuals in the early–mid 1990s to about 2,900 whales in 2014, as this species has recovered from historic whaling impacts . SightinLevels of song occurrence in this feeding and migratory habitat are high, occupying 9 months of the year with temporal coverage reaching as high as 86% of the time during the annual winter peak. Absence of song during summer, when visual sighting levels are high, emphasizes behavioral regulation of song activity. Coincidence of the annual trough in day length with both the annual song peak and evidence of population movement out of Monterey Bay is consistent with the underlying seasonal ecosystem variations and associated migratory patterns required for successful foraging and reproduction. These seasonal patterns observed in the northeastern Pacific are similar to those observed for humpback whales in the southeastern Pacific, northeastern Atlantic, and northwestern Atlantic. The rise of song activity leading into the breeding season is consistent with a central role in reproductive ecology, yet the prevalence of song in feeding and migratory habitats motivates further consideration of the greater spectrum of possible roles in social interaction, cultural transmission, and perception. Favorable foraging habitats that support relatively dense populations of whales may enhance density-dependent influences on song development and learning.Interannual variation in song was great, exhibiting a positive trend over three years during which the temporal coverage of song doubled. Espousing the method of multiple working hypotheses , and witNOAA's National Marine Sanctuaries and National Marine Fisheries Service play a central role in understanding and protecting species and their habitats, with increasing interest in natural and anthropogenic sounds . Passive


T2*)—simultaneously and quantitatively in‐vivo.To study placental function—both perfusion and an oxygenation surrogate (T2* and perfusion measurements in 1 joint perfusion‐oxygenation (PERFOX) acquisition. Joint motion correction and quantification were performed to evaluate changes in T2* and perfusion over GA.Fifteen pregnant women were scanned on a 3T MR scanner. For perfusion measurements, a velocity selective arterial spin labeling preparation module was placed before a multi‐echo gradient echo EPI readout to integrate T2* in all subjects. Areas of high T2* and high perfusion appear to correspond to placental sub‐units and show a systematic offset in location along the maternal‐fetal axis. The areas of highest perfusion are consistently closer to the maternal basal plate and the areas of highest T2* closer to the fetal chorionic plate. Quantitative results show a strong negative correlation of gestational age with T2* and weak negative correlation with perfusion.The optimized integrated PERFOX protocol and post‐processing allowed successful visualization and quantification of perfusion and T2* and perfusion, however, to achieve this, the time per slice is prolonged compared to a perfusion only scan which can potentially limit coverage. The achieved interlocking can be particularly useful when quantifying transient physiological effects such as uterine contractions. PERFOX opens a new avenue to elucidate the relationship between maternal supply and oxygen uptake, both of which are central to placental function and dysfunction.A strength of the joint sequence is that it provides truly simultaneous and co‐registered estimates of local  It supplies the fetus with oxygen and nutrients and ensures the elimination of waste products. It furthermore has essential endocrine and immunological functions. Major pregnancy complications such as pre‐eclampsia, fetal growth restriction, and preterm birth—all carrying a substantial risk of increased morbidity and mortality for both mother and child—are linked with placental insufficiency. Anatomically, the human placenta is composed of 10‐40 functional lobules.Placental insufficiency is linked to smaller than normal vascular lumen of the maternal spiral arteries as a sign of incomplete remodeling. Furthermore, less capillarized, elongated villi can be observedA recent surge in placental MRI studies showed promising results to bridge this gap and allow in vivo assessment of placental function during gestation. The ability of MRI to generate contrasts adapted to microstructure and tissue properties renders this technique ideally suited to visualize the cascade of events within the placenta leading ultimately to placental insufficiency. Among these, perfusion measurements have been performed using a variety of techniques: Intravoxel incoherent motion (IVIM),T2* is of specific interest because there is a well‐established relationship between this parameter and oxygenation through the blood oxygen level dependent (BOLD).T2* as an indicator of oxygen concentration it is not a direct measure. Important confounding factors include microstructural geometry effects, e.g. due to the random diffusion of water molecules around vessels which lead to a reduced BOLD signal around smaller vessels and differences in the oxygen‐hemoglobin dissociation curve between fetal and adult hemoglobin.Relaxometry techniques has been successfully used for oxygenation studies of the placenta.T2* relaxometry and VSASL, allows to study the interaction between maternal perfusion and T2* as a marker fetal oxygen uptake. Quantitative and qualitative results from 15 placentas illustrate the dynamic joint spatial patterns of perfusion and oxygenation in vivo over gestational age.Despite the recent increase in available techniques and interest, current placental imaging studies are often limited by focusing on an individual contrast and a tendency to evaluate parameters averaged over the entire placental volume. Given the complex disease etiology, physiological placenta studies could benefit from multiparametric analyses, that can locally link, e.g. maternal perfusion to the microscopic structure of the villous tree and oxygen exchange. There are, however, 2 significant challenges complicating such described multi‐modal assessments in placental MRI: (a) maternal respiration and fetal bulk movements decrease internal consistency between data acquisitions separated in time (b) examination times need to be kept short to ensure maternal comfort. This study therefore proposes a multidimensional simultaneous integrated assessment of perfusion and oxygenation called PERFOX: combining 2 independent functional MRI techniques, 22.1The study was approved by the local IRB (Riverside Ethics Committee REC 14/LO/1457). A total of 15 pregnant women  28.9/21.9‐38.2 weeks) were included and scanned subsequent to informed consent, in the supine position2‐weighted 2D single shot Turbo Spin Echo sequence and B0 map were acquired in coronal orientation covering the whole uterus. These enabled both image‐based shimmingEach scan session started with initial calibration scans: a T2.2Strategies to deal with motion is of key importance due to the high prevalence of breathing and fetal motion. The image acquisition was thus performed with single‐shot echo planar imaging (ssEPI) to freeze motion within each slice. To limit acoustic noise, the ssEPI sequence was constrained by imposing an echo spacing of 1 ms (i.e. read‐out frequency of 500 Hz), shown previously to minimize acoustic noise on our scanner.2.3cV) and a post‐label delay (PLD), a background suppression (BGS) module consisting of 2 inversion pulses, and the EPI read‐out module. As in conventional implementations of VSASL, the tagging module is spatially non‐selective. However, the gradients in the tagging module are applied along a chosen axis and only blood flowing in this direction is labeled. Labeling in the maternal superior‐inferior direction was judged most effective  in preliminary investigations irrespective of scan plane orientation, so this was adopted for all examinations. Acquisition of control images with the gradients in the tagging module set to zero and subtracting these from labeled images removes the static tissue signal contributions. Each pair of label and control images, acquired in interleaved order is referred to as one dynamic. A consequence of using a 2D multi‐slice acquisition in combination with VSASL is that each slice within the imaging volume is excited at a different time relative to the tagging module. Each slice thus has its own PLD and presents with different degrees of BGS.VSASL,T2* simultaneously by the addition of extra gradient echoes prescribed after the initial echo for each slice. This allows T2* mapping independently for both label and control volumes as depicted in Figure T2* fitting in each slice is acquired within <200 ms. The range of TEs for the multiple echoes was chosen based on placental T2* values, obtained in a previous study (10‐150 ms).This basic VSASL sequence was modified and optimized to deliver information on perfusion and tudy 10‐10 ms.5To assure that the perfusion results are comparable with respect to their position along the axis from maternal basal plate to fetal chorionic plate, the slice acquisition order was adjusted to be anterior‐to‐posterior for anterior placentas and posterior‐to‐anterior for posterior placentas.T2* fitting was reliable and the coverage appropriate. Enforcing a similar maximal PLD for the last slice for PERFOX compared to a ‘separate’ VSASL acquisition resulted in 8 slices, compared to 13 slices  which was used to adjust sequence timings to make sure that all imaged slices had positive signal at the beginning of the read‐out of the first sliceFor the BGS, 3 preliminary T3 mm3, Field‐of‐view 300 × 380 × 20 mm, 8 slices in ascending order, SENSE 2.5, Partial Fourier 0.97, TR = 3500 ms, PLD = 1600 ms, inter‐slice spacing 115 ms, 1 dynamic without BGS and 25 dynamics with BGS (pulse timings 50 ms and 1130 ms), Label 50 ms, G = 13 mT/m, cV = 2 cm/s, total acquisition time 3 min.The imaging parameters for the coronal PERFOX scans were resolution 42.4Nonrigid motion correction was performed in ANTS.T2* fitting were performed as depicted schematically in Figure T2* mapping, the signal values from all echoes were fitted voxel wise to a mono‐exponential decay curve S(t)=S(0)exp(-T2*/TE). Using Levenberg‐Marquart optimization with initial parameters T2* = 100 (ms) and S(0) = S(TE1). Both individual T2* maps for each volume for control/tag volumes, respectively, and averaged T2* maps for control and label volumes were calculated.Once all volumes were aligned, perfusion analysis, and 2 weighting of the labeling module on the perfusion data; it therefore produces a semi‐quantitative quantity related to blood flow facilitating comparison of data from different subjects. This avoids absolute quantification which would require estimation or assumption of blood T1 and T2, since these are highly dependent on blood oxygenation, hematocrit and whether maternal or fetal blood is being considered. We therefore express the perfusion maps in arbitrary units. All displayed results—both the maps and the quantitative results are using these units. By averaging over multiple dynamics the cumulative result is obtained.Perfusion analysis was performed by pairwise subtraction of the label‐control pairs with BGS. The resulting difference images were normalized by the pseudo‐M0. This normalization takes the unsaturated magnetization of the inflowing blood into account and removes the effect of the TT2* and perfusion/M0 over GA. A one‐way ANCOVA was conducted to determine whether there is a statistically significant difference between placental location (anterior/posterior) on T2* respectively on perfusion/M0 when controlling for gestational age.Quantitative evaluation was performed by averaging the values within the ROI to assess the relationship between l subsequent dynamics, where l is the length of the sliding window.All described analysis so far included the cumulative averaged subtraction results from all dynamics. The influence of the number of dynamics on the cumulative perfusion map was evaluated in a subgroup of participants using between 2 and all acquired dynamics for the quantification. The corresponding cumulative maps are displayed alongside each other together with plots from averaged signals from selected ROIs. In addition, a sliding window analysis was performed, whereby the perfusion map is the average over 2.5T2* relaxometry, n = 5; separate VSASL, n = 5; and both separate T2* and VSASL, n = 1. These separate scans were individually optimized for the respective purposes ‐ narrow range of PLD for VSASL over a number of slices sN and ideal spacing of echo times for T2* measurements. Read‐out parameters such as resolution, echo spacing and TR were chosen to be as close as possible between these acquisitions and the PERFOX acquisition to enhance consistency. The T2* acquisitions were performed in the same exam half immediately following the PERFOX scan; the VSASL scan was performed in the second exam half, after repositioning and new shimming. Reproducibility was studied in 3 volunteers where the PERFOX scan was repeated in the second half.Additional experiments were performed to evaluate parameter choice, robustness and versatility of PERFOX on a subset of subjects: (a) separate Finally, in 8 of 15 volunteers a PERFOX scan with higher resolution and axial slice orientation (PERFOX‐HIGH) was performed to explore the ability of the proposed PERFOX technique to visualize even finer details. The different orientation was chosen as discussed above, to allow visualization of the main functional axis of the placenta over a few select slices without the confounding effects of slice‐dependent PLD and BGS variation. The TEs were chosen as  ms.3The joint PERFOX scan was successfully implemented and acquired on all participants: unprocessed images from 1 anterior placenta and 1 posterior placenta are shown in Figure 3.1T2* differences between lobules and septa (tissue sections separating the lobules), result in different anatomical landmarks in the 3rd echo and frequent registration failures affecting also the alignment of the data from the shorter TEs. Better results were consistently achieved with the approach discussed above based on only estimating motion parameters from the volumes acquired at the first TE.Visual analysis of a subset of the initial datasets confirmed that the registration of consecutive echoes was not beneficial: the extensive An example of the usefulness and efficacy of the motion correction is illustrated in Figure The influence of the number of dynamics (control‐label images) is illustrated in Figure 3.2T2* results are consistently illustrated with red‐yellow (low‐high) color scale and perfusion results with dark blue—light blue (low‐high) scale. Resulting perfusion and T2* maps from 1 slice are given in Figure T2* and regions of high perfusion in the coronal planes. While their pattern is similar, the centers of these areas are not spatially co‐localized within each slice. The T2* maps show—in line with previous resultsT2* with a clear peak in the middle and decay toward the outer regions. Perfusion weighted images and T2* maps are illustrated for the axial high resolution joint PERFOX‐HIGH acquisition in Figure T2* are closer to the fetal chorionic plate  and VSALS (top row) appear to correspond. However, their spatial alignment is less clear.In the following, 3.3T2* over the whole organ is plotted against gestational age for all 18 scans in Figure T2* and GA are significantly correlated . There is no significant effect of placental location on T2* after controlling for GA . There is no significant correlation between perfusion/M0 and GA . There is also no significant effect of placental location on perfusion/M0 after controlling for GA . The results from the 3 participants with a repeated scan after re‐positioning and new shimming are highlighted by circles and connected by lines. The mean coefficients of variation for these 3 repeated datasets are 4.6±1.5% (T2*) and 9.8±6.3% (perfusion).Whole placental ROI analysis was performed on all PERFOX scans. The mean T2* maps and the perfusion maps obtained with short TE, perfusion weighted T2* maps and perfusion maps at increasing levels of T2* weighting are shown in Supporting Information Figure T2* map from the control data shows longer T2* values compared to the tagged T2* map—illustrated as well in the difference map. Analysis of all datasets reveals that the ratio between tagged and control T2*, decreases over gestational age (P = 0.0057). Similar analysis of the influence of the BGS on the T2* maps did not show statistical significant differences between T2* maps calculated from non‐BGS and BGS volumes (P = 0.88).The multidimensional data obtained with PERFOX allows several further directions of analysis: beside the conventional non‐perfusion weighted T2* weighting on the perfusion results by calculating the perfusion maps at different T2* weightings. The confounding effect of the T2* contribution to the perfusion map can be completely eliminated by calculating a perfusion map from the proton density maps extracted from T2* fitting. Example results comparing the perfusion map from the 1st TE and the proton density maps are shown in Supporting Information Figure The joint acquisition also allows to assess the effect of 42 T2* was originally exploited combining data from separate acquisitions at multiple echo timesThis study presents a combined sequence for placental perfusion and oxygenation (PERFOX) measurement with required essential post‐processing, mainly motion correction and quantification on 15 pregnant women. PERFOX is the first example of application of this dual‐contrast acquisition to the placenta. A key advantage is the higher consistency within the multimodal dataset, compared to a separate/sequential acquisition as well as the ability to dynamically resolve both essential quantities jointly. ASL measurements have, however, been previously combined with TT2* closer to the fetal chorionic plate. This shift can be best observed in transverse scanning plane due to the curved geometry of the placenta with regard to the main imaging planes. Furthermore, the low T2* on the in‐flowing highly oxygenated maternal blood  compared to the mid‐parenchymal high‐ T2* peaks might indicate that these observed high T2* regions are linked not only to oxygenation state but to either blood flow velocity, exchange or properties of fetal hemoglobin. The exact physiological pathway resulting in this observed behavior remains however unclear, but dynamic multi‐contrast techniques such as the acquisition presented here might help to shed light on these processes.The simultaneous acquisition allows to observe a clear spatial pattern in all our participants, with areas of high‐perfusion centered close to the maternal basal plate and areas of high The analysis provided here, showed that the number of required dynamics for stable perfusion signal in the placenta is in the range of 5‐8 for the chosen acquisition parameters. This allows either to reduce the number of dynamics and thus limit the required acquisition time, or a dynamic assessment using a sliding window analysis as illustrated in Figure The high contrast to noise ratio resulting from high perfusion values observed in the placenta are essential for this. These observations will not directly translate to less blood‐rich organs such as the brain, where a higher number of dynamics is required for robust perfusion visualization, resulting in coarser temporal resolution.T2* and weak negative correlation between perfusion and gestation are in line with those observed separately in previous studies.The observed strong linear decrease over gestation in One prior study showed differences in perfusion between lateral and supine positioning.T2* relaxometry with multiple echoes in quick succession.Recent placental ASL studies used 3D readoutsT2* mapping and narrow range of PLDs for all slices—the joint acquisition inevitably forces compromises on these constraints. Therefore, i.e. only 3 echo times for T2* mapping with lower maximal TE of 93 ms (instead of 148ms) and a reduced coverage of 8 slices (instead of 13) were chosen to keep the acquisition time for all slices at all 3 echo times as compact as possible. Nevertheless, the obtained functional maps illustrate usable data of good quality. The Rician noise distribution in conventional MRI images, approaching Gaussian distribution only for high signal‐to‐noise ratio (SNR), is important to consider for the T2* fits. Low SNR is associated with longer echo times, which result, e.g. from longer EPI trains to achieve higher resolution multi‐echo T2* scans or if more than 4 echoes are acquired for multi‐exponential multi‐compartment fits. However, in our case, the requirement to reduce PLD resulted in only 3 echo times acquired at comparably low resolution of 3 mm. The short TEs ensure robust mono‐exponential fitting, but do, however, not support higher order fitting.Compared with more conventional separate acquisitions which allow individual optimization of sequence parameters for each modality—e.g. 4 echo times spanning a wide range for 2‐dependent signal decay. With our 50ms‐long module and assuming T2 of blood to be roughly 170 ms, we have a 35.5% signal loss/module. Less oxygenated blood with lower T2 will experience an even higher signal reduction. Finally, the stricter specific absorption rate (SAR) limitation for fetal studies puts a time penalty on the DVSASL technique where 2 additional 90‐degree pulses plus an adiabatic refocusing pulse are required. In our case adding the 2nd module raised the minimally achievable repetition time from 3.5 s to 6.4 s. This would thus either increase the acquisition time or decrease the number of acquired label‐control pairs. Evaluation of dual VSASL vs. the protocol used in this study is underway.VSASL often employs a second velocity selective module immediately before the acquisition  and the 2 PERFOX variants with 8 slices used in the paper (standard PERFOX in green and PERFOX‐HIGH in red). The first echo is marked by a large star, second and third echoes by smaller starsFIGURE S2 Illustration of the influence of the different scan orientations on the acquired signal. (A) Schematic illustration of the 2 scan orientations employed in this paper—coronal and transverse. (B‐C) Control images from the coronal (red background) and transverse (green background) acquisitions, each is also displayed reformatted in the non‐native orientation. (B) displays the results without and (C) with background suppression. Finally, (D) displays a zoom into both acquisitions together with yellow arrows to illustrate the direction of increasing PLDFIGURE S3 Results from a coronal PERFOX scan at GA 29+1 weeks. Five consecutive slices are shown for the anatomical GE‐EPI volume (first row), the perfusion maps (second row) and the T2* maps (third row)FIGURE S4 A, T2* maps calculated from the control volumes, labeled volumes and difference in T2* between the 2. B, Perfusion maps at the 3 different echo times TE acquired in PERFOX. C, Evaluation over all subjects of the mean T2* values from tagged and control volumes relative to the mean T2* from control volumesFIGURE S5 Perfusion maps obtained from the proton density maps and from the data from the 1st echo time together with difference imageClick here for additional data file.


The autonomic nervous system (ANS) has a significant influence on the structural integrity and electrical conductivity of the atria. Aberrant activation of the sympathetic nervous system can induce heterogeneous changes with arrhythmogenic potential which can result in atrial tachycardia, atrial tachyarrhythmias and atrial fibrillation (AF). Methods to modulate autonomic activity primarily through reduction of sympathetic outflow reduce the incidence of spontaneous or induced atrial arrhythmias in animal models and humans, suggestive of the potential application of such strategies in the management of AF. In this review we focus on the relationship between the ANS, sympathetic overdrive and the pathophysiology of AF, and the potential of sympathetic neuromodulation in the management of AF. We conclude that sympathetic activity plays an important role in the initiation and maintenance of AF, and modulating ANS function is an important therapeutic approach to improve the management of AF in selected categories of patients. Potential therapeutic applications include pharmacological inhibition with central and peripheral sympatholytic agents and various device based approaches. While the role of the sympathetic nervous system has long been recognized, new developments in science and technology in this field promise exciting prospects for the future. The heart is extensively innervated and effectively regulated by the autonomic nervous system (ANS) through its sympathetic and parasympathetic branches . The carThe extrinsic nerves run through the hilum of the heart along the great cardiac vessels and divide into seven epicardial subplexi, the intrinsic neural pathways of the ANS . Small nAutonomic nervous system activation has been well-known as a central determining factor of atrial arrhythmogenesis, . Studies2+-inward current and upregulation of inward rectifier K+ currents   . Both co2+) . During 2+) . On the 2+) .Intense atrial fibrosis formation and cardiomyocyte hypertrophy are common features of structural remodeling. Atrial tissue fibrosis damages electrophysiological cell-to-cell coupling and conduction . Long-teSympathetic activation also plays a major role in atrial arrhythmias following cardiac surgeries and post-operative (post-op) AF is associated with reduced long term survival with cardiac surgeries such as the coronary bypass and valvular surgeries especially the aortic valve replacement . Often fGiven the contribution of sympathetic overdrive in the development of AF, sympathetic inhibition represents a logical therapeutic approach in the management of AF and the frequently coexisting hypertension, thereby alleviating the associated cardiovascular mortality and morbidity. Autonomic dysfunction characterized by sympathetic overdrive in scenarios of organic heart disease exhibits both electrical and structural remodeling of atrial myocardium in AF. Pharmacological sympatholysis can be achieved by using drugs such as clonidine and moxonidine. Clonidine is a centrally acting α2-adrenergic agonist that supresses the sympathetic outflow in the lower brainstem , the preMoxonidine seems specifically useful in obesity related hypertension where the sympathetic overdrive sustains both obesity and BP elevation. With the well-established relationship between abdominal obesity, the metabolic syndrome, and the development of AF, obese hypertensives are at a greater risk for AF. Studies have identified that autonomic dysfunction occurs early in the pathophysiology of AF and precedes the development of metabolic abnormalities such as insulin-resistance and obesity  which inSympathetic blockade at the periphery can also be achieved by beta-adrenergic blockers. Though beta-blockers are not generally regarded as membrane stabilizing agents, they delay atrial repolarization and protect against AF. It was speculated that beta-blockers suppress the pulmonary vein ectopy that triggers AF  as well Other interventions include device-based therapeutic approaches to modulate ANS to lower central sympathetic nerve activity such as renal denervation (RDN) and carotid body ablation. These approaches are primarily aimed at reducing sympathetic activity and BP in resistant hypertensive patients but are now investigated as potential treatment strategies in the context of AF.Recently, the AFFORD study, a single-arm pilot study including 20 patients with symptomatic paroxysmal or persistent AF, suggested that RDN alone was safe and able to decrease AF burden in min/day as measured using an implantable cardiac monitor (ICM) at 12-month follow-up accompanied by an improvement in quality of life . A cliniP = 0.0021) and ventricular rate response in pigs with permanent AF. The authors described a reduction of 24% in ventricular rate response in the treated pigs vs. sham, as well shorter AF episodes post-RDN compared with sham  (Mechanistic studies demonstrated that modulation of the SNS via RDN improved AF control . Linz et 0.0091) ,b. Effec 0.0091) . RDN pre 0.0091) . Recentl 0.0091) .P = 0.0251) or non- CKD patients who underwent PVI  over 22.4 ± 12.1 months following intervention. In addition, they found an improvement in echocardiographic parameters such as indexed left atrial volume, left ventricular end-diastolic diameter, and left ventricular mass index in patients who underwent RDN compared to baseline and to other groups. Another important finding was that patients with CKD stage 4 who underwent only PVI (64.41%) demonstrated a higher rate of AF recurrence than those subjected to PVI + RDN  , Kiuchi et al., applying an extensive ablation technique reported the incidence of AF recurrence. It was higher in CKD patients treated with PVI alone (61.5%) than in CKD patients treated with PVI + RDN  .Chronic kidney disease and AF share risk factors and putative mechanisms suggesting that common pathophysiologic processes may drive both pathologies. One possible common link between AF and CKD is activation of the renin–angiotensin–aldosterone system (RAAS) . Angiote18FDG (fluorodeoxyglucose) – uptake in the brainstem, left stellate ganglion nerve activity and atrial tachyarrhythmic events. It was proposed that neural remodeling in the brain stem and stellate ganglion may partially explain the described antiarrhythmic effects of RDN (Trans-synaptic degeneration is a phenomenon in the central and peripheral nervous system that may remain active both at the level of the insult and in remote brain structures for as long as 1 year following trauma (s of RDN . Trans-sg trauma  resulting trauma .trans-synaptic degeneration (Since the sympathetic preganglionic neurons that project to the stellate ganglion are dispersed in spinal cord segments sections T1–T10 , they haneration , as the neration . RDN mayneration .Pulmonary vein isolation with ganglionated plexi ablation has been used in autonomic modulation of interactions between the systemic and intrinsic cardiac ANS. PVI combined with autonomic ganglia modification significantly improved success rates after PVI compared to PVI alone . In animRecent studies have reported that an abundance of epicardial fat is associated with direct adipocyte infiltration into the underlying atrial myocardium . MoreoveStudies demonstrate that stimulation of the stellate ganglion increased sinus rate and predisposes to atrial arrhythmias ,b. IncreIn patients undergoing cardiac surgery and cardiopulmonary bypass, high thoracic epidural anesthesia was found to markedly reduce sympathetic tone  and the Hypersensitive chemoreceptors result in sympathetic excitation. Enhanced chemoreflex sensitivity potentially increasing central sympathetic drive was observed in animal models of pacing-induced congestive heart failure . SurgicaEnhanced sympathetic activation increases circulating catecholamines and causes hypertension and associated complication such as AF and congestive heart failure. Hypertension often coexists with comorbidities like obesity, metabolic syndrome, and obstructive sleep apnea that further exaggerate and sustain the sympathetic overdrive. Substantial evidence indicates that targeting sympathetic overactivity either by pharmacotherapy or device-based interventions seems to be a logical and useful approach for the management of AF. Sympathetic ablation by RDN appears to be a promising strategy to achieve atrial antiarrhythmic effects in animal models and humans. While carotid body ablation is a proven strategy to attenuate sympathetic overdrive, the potential anti-arrhythmic effects are yet to be investigated in future studies. Other techniques employed to reduce sympathetic activity are applied in specific conditions such as stellate blockade in high-risk patients and following myocardial infarction, ganglionic plexus ablation to lower AF recurrence in patients following circumferential pulmonary vein isolation, and high thoracic epidural anesthesia in post-surgical AF management. However further clinical studies are needed to substantiate the role of various sympatholytic approaches in the management of AF.RC and MS have drafted the manuscript. MK, JH, and VM have researched data, contributed to inidvidual sections, and critically reviewed the manuscript.MS is supported by an NHMRC Research Fellowship and has received consulting fees, and/or travel and research support from Medtronic, Abbott, Novartis, Servier, Pfizer, and Boehringer-Ingelheim. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.


To assess the safety and efficacy of percutaneous closure of perimembranous ventricular septal defect (PmVSD) using patent ductus arteriosus (PDA) occluders.Widespread use of conventional PmVSD closure devices has been limited by unacceptable high rate of complete heart block (CHB). The elegant design of PDA occluders is supposed to ease implantation, increase closure rate and minimize damage to adjacent structures. Thus, PDA occluders may reduce complications, especially the CHB, and offer a good alternative for PmVSD closure.From September 2008 to October 2015, patients who underwent attempted percutaneous VSD closure using PDA occluders were included in the study. Patient demographics, echocardiography measurements, procedure details and follow-up data until October 2017 were collected.In total, 321 patients with a mean age of 15.5±12.6 years and mean a weight of 33.3±20.5 kg were included in this study. The mean defect size was 4.8±2.1 mm. Implantation was successful in 307 (95.6%) patients. The median follow-up time was 63 months (24 to 108 months). The closure rates were 89.5%, 91.5%, and 99.3% after the procedure 24 hours, 6 months and 2 years, respectively. Major complications occurred in 5 (1.7%) patients during the procedure and follow-up, including persistent CHB in 2 (0.7%) patients and device embolization in 3 (1.0%) patients. No death, disability, or other major complication was detected.Percutaneous closure of PmVSD using PDA occluders is feasible, safe and efficacious in selected patients. Ventricular septal defect (VSD) is among the most common congenital heart diseases in both children and adults . AlthougPDA occluders are single disc devices based on nitinol wire meshes and originally designed for percutaneous PDA closure. They combine the ease of implantation with a high occlusion rate and a low rate of complication , 16. OwnS1 File). Inclusion criteria for percutaneous PmVSD closure using PDA occluders were left to right shunt, Qp/Qs > 1.5, age > 5 months, weight > 5 kg, and at least one of the following: dilation of the left ventricle or left atrium on two-dimensional echocardiography, symptoms of heart failure, failure to thrive or cardiomegaly on chest radiography. Patients with concomitant lesions requiring cardiac surgery, pulmonary vascular resistance >8 Wood units, significant aortic regurgitation, aortic valve prolapse and right-to-left shunt were excluded from device closure. The study flow chart is presented in Fig 1.From September 2008 to October 2015, 321 patients (including 130 patients under 6 years of age), who underwent attempted percutaneous closure of VSD using PDA occluders at Vietnam National Heart Institute (n = 221), Ha Noi Medical University Hospital (n = 60), Ha Noi Heart Institute (n = 25) and Quang Nam Central General Hospital (n = 15) were retrospectively included in this study . A polyester fabric is sewn inside the device with polyester thread, inducing thrombosis that closes the communication. The right ventricular (RV) end of the device will fit in the RV side of the PmVSD while the bigger left ventricular (LV) end and retention disc provides secure positioning in the LV ampulla of the defect. The Amplatzer Duct Occluder has available sizes of 6/4, 8/6, 10/8, 12/10, 14/12 and 16/14 mm, where the first number refers to the LV end diameter and the second number indicates the RV end diameter of the device. The biggest size of the Cocoon Duct Occluder is 20/18 mm and the Cera PDA Occluder size is up to 24/22 mm. The selected device size (RV end diameter) was 2 mm bigger than the smallest PmVSD diameter measured on echocardiography and left ventriculogram. The delivery system includes a delivery catheter (ranges from 5 to 8 French), dilator, delivery cable, loading device, hemostasis valve and plastic vise.The three types of PDA occluders used in this study were Amplatzer Duct Occluder , Cocoon Duct Occluder , and Cera PDA Occluder . These devices have similar self-expanding and self-centering nitinol wire mesh design with a small single retention disk and a cylindrical main body . Location, size of the VSD, and its relationship with the aortic valve were assessed. The VSD size , VSD ampulla size  and the VSD length were measured.An informed written consent was obtained from all patients or their guardians before intervention. The procedure was performed under general anesthesia in all infants and small children or local anesthesia in the older patients. Access was obtained through the right femoral vein and right femoral artery. Heparin 100 UI/kg and prophylactic antibiotic were given intravenously before standard right and left cardiac catheterizations were performed. Left ventriculography at 55° left anterior oblique and 30° cranial projection was used to profile the defect . Through this loop, the delivery catheter was introduced from the venous access to the RV, LV, and to the ascending aorta . Left ventriculogram, aortogram, and echocardiography were performed before release to confirm proper device position.Through the VSD, a 0.35-inch Terumo guidewire  was introduced from the LV to RV, right atrial, superior vena cava, and was subsequently captured by a snare advancing from the femoral vein to make an arteriovenous loop , LV diastolic diameter (LVDd), left atrial (LA) diameter, pulmonary systolic pressure, sub aortic rim length and the systolic gradient through the defect. Procedural details recorded included procedure time, fluoroscopy time, pulmonary pressure, Qp/Qs ratio, the defect size on left ventriculogram, and the type and size of devices used. Additionally, the reasons for aborted procedures or failed implantations were also documented.th percentile for age and sex. On echocardiography, LA enlargement was defined as a LA to aortic ratio > 1.5 in the long-axis parasternal view. LV enlargement was defined as LVDd ≥ 2 standard deviation for the body surface area. A residual shunt was considered to be present if Color-Doppler echocardiography showed a left to right jet across the VSD. It was classified as small (jet ≤1 mm), moderate (jet 2–4 mm), or large (jet ≥4 mm).Heart failure was diagnosed using Framingham criteria. Failure to thrive in children was defined by weight less than the 5Major complication was defined as procedure-related death, life-threatening adverse events, or those required surgery, such as device embolism, myocardial perforation, vessel rupture, severe residual shunt, severe hemolysis, valvular injury or persistent complete heart block that required permanent pacemaker insertion. Complications categorized as minor were non-fatal complications and regressed spontaneously or with medication such as access site hematoma, hemolysis that only required medication, blood transfusion because of blood loss, transient complete heart block, bundle branch block, fascicular block, first degree or Mobitz I type AV block, rash, fever, etc. Total complication was the sum of minor and major complications.Procedure success was defined by the absence of major complications and appropriate position of the implanted device on echocardiography 24 hours after the procedure.Statistical analyses were performed with SPSS Statistics 23.0 . Continuous variables are expressed as mean ± standard deviations or median and quartiles. Categoric data are presented as frequencies and percentages.Table 1. The mean age was 15.5±12.6 years . The mean weight was 32.4±20.4 kg . Of these patients, 22.7% had symptoms of heart failure, 27.1% had recurrent respiratory infection, 32.4% failed to thrive, and only 18.7% were asymptomatic. On echocardiography, the mean VSD size was 4.3±1.3 mm, the mean pulmonary artery systolic pressure was 35.3±7.8 mmHg, mean sub aortic rim was 3.4±1.4 mm and 156 (48.6%) patients had PmVSD with aneurysm. Cardiomegaly on chest radiograph was detected in 74 (23.1%) patients. One patient who had concomitant ASD and two patients who had PDA were percutaneously closed during the index procedure.From September 2008 to October 2015, 321 patients  underwent attempted percutaneous closure of PmVSD using PDA occluders. The baseline characteristics of participants are presented in  The mean procedure time was 45.8±16.9 minutes. The mean Qp/Qs ratio measured on catheterization was 2.1±0.6. On left ventriculography, mean VSD size was 4.8±2.1 mm (from 2.0 to 14.0 mm), mean VSD length was 5.9±1.6 mm (from 3.6 to 12.0 mm) and mean sub aortic rim was 3.5±1.8 mm (from 1.2 to 8.0 mm). Altogether, 97 Amplatzer Duct Occluders, 149 Cocoon Duct Occluders and 61 Cera PDA Occluders were implanted.The procedure and device data are presented in Table 3. Of the 321 patients included in this study, 307 (95.6%) patients had successful implantation with the PDA occluders. Immediate closure of the defect without any residual shunt after deployment was achieved in 236 (77.6%) patients. Further echocardiographic follow-up showed that the closure rate gradually increased up to 89.5%, 91.5%, 97.4% and 99.3% at 24 hours, 6months, 1 year, and 2 years after the procedure, respectively.The procedure success and closure rates are presented in Table 4. The median follow-up time was 63 months (24–108 months). Most of the adverse events were categorized as minor complication (11.7%). Major complications occurred in 5 (1.7%) patients. Device embolization was detected in 3 (1.0%) patients. In the first case, a 16 months old boy, the device dislocated to the LV out flow tract 3 days after the procedure. In the two other cases, a 3-year-old girl and a 16-year-old boy, the devices embolized to the RV 36 hours and 6 weeks after deployment, respectively. These patients underwent cardiac surgery for device removal and VSD closure with good recovery. Persistent CHB that required permanent pacemaker insertion occurred in 2 (0.7%) patients, including a 6-year-old boy at 15 days and a 40-year-old female at 5 months after the procedure. There was no death, disability or other major complication detected.The adverse events during the procedure and follow-up are presented in Percutaneous closure of VSD using the conventional PmVSD occluders, either symmetrical or asymmetrical double disc design, has largely been abandoned because of unacceptable high CHB rate documented in the literature , 19–21. Table 5). For percutaneous VSD closure in these small children, the PDA occluders with a small delivery system (6–8 French), the ease of implantation and, experienced operators are crucial keys to increase procedural success rate and minimize the complications.Previous studies showed that infants and small children had lower procedure success and higher major complication rates of percutaneous PmVSD closure , 20, 24.Careful defect sizing and proper device selection are also important to reduce the complications of VSD closure , 26. WhiAnother important factor that greatly impacted the success of the procedure was the sub aortic rim length. A short aortic rim makes the implanted device less stable, and the retention disc may compromise and cause damage to the aortic valve. For cases with a small aortic rim and no aneurysmal tissue, we might choose a smaller device, accepted mild to moderate residual shunt to minimize the damage to aortic valve. However, respecting that surgical VSD closure is currently the treatment of choice and patient safety is the priority, in cases with unstable device position (6 cases), severe residual shunt (2 cases) or aortic valve compromised (1 case) before release, we stopped the implantation and recommended cardiac surgery for the patients.The defect shape also has an important influence during the PmVSD closure procedure. In this study, 40.5% of patients had PmVSD with aneurysms. For these cases, the conventional double disc device size must be large enough to cover the whole aneurysm and may cause further complications . HoweverS1 Fig), along with the improvement of clinical presentations observed in most patients during the follow-up showed good efficacy of the PDA occluders for PmVSD closure.In this study, the procedure success 95.6%) and the immediate closure rate (77.6%) were high and comparable to those of the other studies, using the conventional double disc devices (such as Amplatzer Membranous VSD Occluder) .6% and t, 29, latDevice embolization occurred in 3 patients during the hospital stay and follow-up. In the first patient, a 16-month-old baby, the device (Cera PDA Occluder) dislocated to the LV out flow tract 3 days after the procedure. In two other patients, a 3-year-old girl and a 16-year-old boy, the devices (both Cocoon Duct Occluder) embolized to the RV 36 hours and 6 weeks after deployment, respectively. These patients then underwent cardiac surgery for device removal and VSD closure with good recovery. Noticeably, all device embolization occurred in the first years of this study. The reasons might be errors in defect size estimation that lead to under-sized device selection or the problems in the device deployment technique that lead to suboptimal device positioning, which occurred during the early phase of the study. Furthermore, these cases had high risks for device embolization, such as defect size > 5 mm, aortic rim < 2 mm and moderate residual shunt existed before device release. Therefore, careful patient selection, gaining operators experience and improving closure techniques are important to reduce device embolization in percutaneous PmVSD closure with PDA occluders.S2 Fig). In comparison with percutaneous VSD closure using conventional devices, the incidence of CHB after surgical VSD closure in the literature was lower, ranging from 0% to 2.2% [. In other words, percutaneous PmVSD closure using duct occluders may be a good alternative therapy to surgical closure in suitable patients.The huge cornerstone that makes the widespread use of percutaneous VSD closure with devices has been limited is the unacceptable high rate of CHB in the literature , 33, 34. to 2.2% –49, and  to 2.2% . The incThis was a retrospective study with a limited number of participants and a wide age range. Besides, the devices were personally selected by the operators based on the preference, availability, and familiarity with these devices. Furthermore, every procedure was performed with at least one operator that had copious experience in VSD closure; therefore, the outcomes of the procedures in this study might not represent routine practice. Even though this was a retrospective study, the strict protocol of percutaneous PmVSD closure in each institute before, during and after the procedure made the collected data comprehensive and accurate.Percutaneous closure of PmVSD using PDA occluders is feasible, safe and efficacious in selected patients. More improvement of device design, operators experience, and implantation techniques along with careful patient selection may further minimize the drawbacks and make percutaneous PmVSD closure with suitable devices become an acceptable alternative to cardiac surgery in the future.S1 File(XLSX)Click here for additional data file.S1 Fig(TIF)Click here for additional data file.S2 Fig(TIF)Click here for additional data file.