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Accurate, detailed, and up-to-date information on cropland extent is crucial for provisioning food security and environmental sustainability. However, because of the complexity of agricultural landscapes and lack of sufficient training samples, it remains challenging to monitor cropland dynamics at high spatial and temporal resolutions across large geographical extents, especially for places where agricultural land use is changing dramatically. Here we developed a novel cost-effective annual cropland mapping framework that integrated time-series Landsat imagery, automated training sample generation, and machine learning and change detection techniques. We implemented the proposed scheme to a cloud computing platform of Google Earth Engine and generated China’s annual cropland dataset (CACD) at a 30 m spatial resolution for the first time. Results demonstrated that our approach was capable of tracking dynamic cropland changes in different agricultural zones. The pixel-wise F1 scores for annual maps and change maps of CACD were 0.79±0.02 and 0.81, respectively. A further cross-product comparison in terms of accuracy assessment, correlations with statistics, and spatial details indicated the precision and robustness of CACD than other datasets. According to our estimation, from 1986 to 2021, China’s total cropland area expanded by 30,300 km2 (1.79 %), which underwent an increase before 2000 but a general decline between 2000–2015 and a slight recovery afterward. Cropland expansion was concentrated in the northwest while the eastern coastal region experienced substantial cropland loss. In addition, we observed 419,342 km2 (17.57 %) of croplands that were abandoned at least once during the study period. The consistent, high-resolution data of CACD can support progress toward sustainable agricultural use and food production in various research applications. The full archive of CACD is freely available at https://doi.org/10.5281/zenodo.7936885 (Tu et al., 2023a).

Additional file 1. Additional figures and tables.

Nitrogen dioxide (NO2) is one of the most important atmospheric pollutants. However, current ground-level NO2 concentration data are lack of either high-resolution coverage or full coverage national wide, due to the poor quality of source data and the computing power of the models. To our knowledge, this study is the first to estimate the ground-level NO2 concentration in China with national coverage as well as relatively high spatiotemporal resolution (0.25 degree; daily intervals) over the newest past 6 years (2013-2018). We advanced a Random Forest model integrated K-means (RF-K) for the estimates with multi-source parameters. Besides meteorological parameters, satellite retrievals parameters, we also, for the first time, introduce socio-economic parameters to assess the impact by human activities. The results show that: (1) the RF-K model we developed shows better prediction performance than other models, with cross-validation R2 = 0.64 (MAPE = 34.78%). (2) The annual average concentration of NO2 in China showed a weak increasing trend . While in the economic zones such as Beijing-Tianjin-Hebei region, Yangtze River Delta, and Pearl River Delta, the NO2 concentration there even decreased or remained unchanged, especially in spring. Our dataset has verified that pollutant controlling targets have been achieved in these areas. With mapping daily nationwide ground-level NO2 concentrations, this study provides timely data with high quality for air quality management for China. We provide a universal model framework to quickly generate a timely national atmospheric pollutants concentration map with a high spatial-temporal resolution, based on improved machine learning methods.

Structures may experience ice-induced vibrations under a wide range of ice conditions. This paper presents a statistical analysis of ice-induced forces on the Norströmsgrund lighthouse. A total of 61 measured events of ice-induced frequency lock-in (FLI) vibrations from 2001 until 2003 are considered. For each event, a smoothing algorithm for joint input-state (JIS) estimation is used to identify the time series of ice-induced dynamic forces based on measured accelerations. The smoothing algorithm is validated by comparing the identified dynamic force with the measured dynamic force. Statistical analysis on these 61 events indicates that the identified force directions agree well with the observed ice-drift directions. However, a universal relation between peak force and ice thickness or ice velocity is not found. Significant peak forces are likely to occur under ice conditions with ice thickness between 0.65m and 0.85m and ice velocity ranging from 0.042m/s and 0.05m/s. © 2019 Port and Ocean Engineering under Arctic Conditions. Available at http://www.poac.com/PapersOnline.html

Currently, the development of offshore wind energy is mainly in shallow or intermediate water, where bottom-fixed substructures (e.g. monopiles and jackets) are mainly used. In harsh environmental conditions at certain locations, these substructures are exposed to plunging breaking waves, which cause slamming forces. A slamming force features a high impact force within a short time. It can affect the structural integrity and the fatigue life of Offshore Wind Turbines (OWTs). Slamming forces on cylindrical structures have been widely studied, while the investigations regarding these forces on OWT jacket substructures are limited. This study addresses the statistical characteristics of slamming forces on OWT jacket substructures and develops a global slamming force model, based on the large-scale experimental data from the WaveSlam project. Three methods are developed to reconstruct slamming forces on the jacket model, including the optimization-based deconvolution (ODC), vertical approach and extended vertical approach. The vertical approach, which is based on linear regression, is more robust and easier to use than the state-of-the-art horizontal approach that uses deconvolution techniques. The vertical approach can be applied to reconstruct the time series of both local and global slamming forces. A plunging breaking wave impacts different locations on the braces of the jacket model at different instants in a more or less random order. Statistical analysis indicates that both local and global slamming forces exhibit high variability for the given wave condition, which is controlled in the laboratory. This variability contributes to the uncertainties of the slamming forces, so it is important and should be considered. A global slamming force model is proposed based on the statistical analysis of the experimental data. The force model involves five parameters, including two exponential parameters and three dimensionless coefficients for the expressions of wave-dependent parameters. Given a sea state, this force model provides a deterministic and conservative prediction of global slamming force time series, which inherently have random features. Three major aspects regarding the application of slamming forces to OWT simulations are discussed, including the detection of slamming events, the calculation of slamming loads and the integration of slamming loads in fully coupled analysis. A supervised machine learning approach is proposed for the detection of plunging breaking waves. A classifier is trained with wave elevation data by using logistic regression algorithm. The classifier has a better performance than the classical McCowan breaking wave criterion.

Background: While enteral nutrition (EN) is the preferred route of nutrition support, and total EN often fails to meet the nutritional needs of patients. A combination of multiple nutritional strategies can reach nutritional goals earlier and improve clinical outcomes. Methods: Totally 108 critically ill patients with a body mass index (BMI) of Results: There were no significant differences in albumin, urea nitrogen, alanine aminotransferase, fasting blood glucose, and triglyceride between the EN group and the SPN group before the nutritional support therapy (P>0.05). After the treatment, the albumin level was significantly higher in SPN group than in EN group (P 0.05). The actual calories and protein intakes in the SPN group were significantly higher than those in the control group (both P 0.05). Conclusions: SPN can improve the caloric and protein intakes, shorten the duration of mechanical ventilation, LOS in ICU, and LOS in hospital, and reduce the incidences of infection complications without apparent impact on blood lipid and sugar profiles or liver/kidney functions.

In this paper, a series of linear-dendritic block copolymers allyloxy poly(ethylene glycol) polyglycerol (APEG-PG-(OH)n) copolymer, was synthesized by anionic polymerization of glycerol using allyloxy poly(ethylene glycol) (APEG). The polymers were characterized by FT-IR and 1H NMR. The polymers were tested as novel environment-friendly inhibitors for industrial cooling water circulation. The performance of AA/APEG-PG-(OH)n on inhibition of calcium phosphate and calcium carbonate precipitation was studied by static scale inhibition tests. It was shown that AA/APEG-PG-(OH)n exhibited excellent ability to control inorganic minerals, with approximately 99 % calcium phosphate inhibition and 85 % calcium carbonate inhibition at levels of 4 and 10 mg/L AA/APEG-PG-(OH)n, respectively. The effect on formation of calcium phosphate and calcium carbonate was investigated with combination of scanning electronic microscopy (SEM), transmission electron microscopy (TEM), X-ray powder diffraction (XRD) analysis, respectively.

Additional file 1. Specified UPLC conditions, resulting chromatograms and analytical data including NMR, UV and MS spectra for the purified natural products.

Repolarization Changes During SVT. Introduction: Previous literature has documented the association between narrow QRS supraventricular tachycardia (SVT) and pronounced ST-T segment change. The aim of this study was to evaluate repolarization changes during SVT initiation and demonstrate the possible mechanism. Methods and Results: Fifty-one consecutive patients (20 men and 31 women; mean age 46.1 ′ 16.4 years) with narrow QRS SVT (32 patients with AV nodal reentrant tachycardia and 19 patients with AV reentrant tachycardia) were included. We retrospectively analyzed the intracardiac recordings and ST-T segment changes on 12-lead surface ECGs during SVT initiation. Twenty-six (51%) patients developed ST segment repolarization changes during SVT initiation. Patients with shorter baseline sinus cycle length, shorter tachycardia cycle length, elevated systolic blood pressure before tachycardia induction, and greater reduction of systolic blood pressure had a higher incidence of repolarization changes. However, multivariate analysis showed that reduction of systolic blood pressure after SVT induction was the only independent predictor of repolarization changes. Furthermore, the maximal degree of ST segment depression during SVT correlated with the reduction of systolic blood pressure (r = 0.75, P < 0.001). Conclusion: Repolarization changes during SVT initiation were caused mainly by concurrent hemodynamic change after SVT initiation with abrupt cycle length shortening.

Paroxysmal atrial fibrillation (PAF) can be initiated by ectopic activation from the crista terminalis. The crista terminalis conduction gap is also a critical isthmus in atrial reentrant arrhythmias like upper and lower loop reentry. The aim of this study was to investigate the mechanism and results of catheter ablation for complex atrial arrhythmias originating from the crista terminalis using the noncontact mapping system (NCM). The study population consisted of six patients (5 men, 1 woman; 70 +/- 9 years) with drug refractory PAF and typical/atypical atrial flutter. NCM identified the earliest ectopic activation originating from the crista terminalis in these six patients. The reentry circuit of atypical atrial flutter propagated around the upper crista terminalis in five patients, and lower crista terminalis in one patient. The reentry circuit of atypical atrial flutter and the initial reentry circuit of AF conducted through the crista terminalis gap in all patients. Radiofrequency applications were delivered on the sites of ectopy, which initiated AF. Substrate modification was also performed over the crista terminalis gap (six patients) and cavotricuspid isthmus (three patients) responsible for the reentry. During a mean follow-up of 9 +/- 5 months (range 5-18 months), five patients were free of AF without antiarrhythmic drugs, and one patient did not have AF or atrial flutter using propafenone. NCM demonstrated the mechanism of crista terminalis ectopy-initiating AF and associated typical/atypical atrial flutter. Catheter ablation of crista terminalis ectopy and substrate for the reentry guided by NCM successfully eliminated these atrial arrhythmias.

Objectives This study was aimed at evaluating the efficacy of non-contact mapping and ablation of non-incisional atypical right atrial (RA) flutters. Background The majority of atypical RA flutters were reported in patients after surgical incision of the RA. Methods The study group consisted of 15 patients (61 ± 13 years, 8 males) with atypical atrial flutter (AFL). The RA activation during AFL was delineated using a non-contact mapping system (EnSite 3000 with Precision Software, Endocardial Solutions, St. Paul, Minnesota). The narrowest part of each reentrant circuit was targeted using radiofrequency energy. Results In all 15 patients, non-contact mapping showed AFLs confined to the RA with RA activation time accounting for 100% of the cycle length (210 ± 19 ms). During single-loop re-entry in seven patients, the activation wave front circulated around the central obstacle (CO) in the anterolateral wall with conduction through the channel between the CO and the crista terminalis (CT). During figure-of-eight re-entry in eight patients, simultaneous upper and lower loop re-entry through the conduction gap in the CT was found in four patients, and simultaneous upper loop and free-wall single-loop re-entry was observed in four patients. Radiofrequency ablation of the free-wall channel and/or CT gap was effective in eliminating these AFLs in 13 patients. During a follow-up of 16.8 ± 3.8 months, two patients had recurrence of left AFL, and one had recurrence of atrial fibrillation. Conclusions Atypical RA flutters could arise from single-loop or double-loop figure-of-eight re-entry. Radiofrequency ablation of the free-wall channel and/or the CT gap was effective in eliminating these arrhythmias.

Objectives The purpose of this study was to investigate the characteristics of the second component of local virtual unipolar electrograms recorded at the ablation line during coronary sinus (CS) pacing after radiofrequency ablation (RFA) of the cavotricuspid isthmus (CTI) for typical atrial flutter (AFL). Background Radiofrequency ablation of the CTI can produce local double potentials at the ablation line. The second component of unipolar electrograms represents the approaching wavefront in the right atrium opposite the pacing site. We hypothesized that the morphologic characteristics of the second component of double potentials would be useful in detecting complete CTI block. Methods Radiofrequency ablation of the CTI was performed in 52 patients (males = 37, females = 15, 62 ± 12 years) with typical AFL. The noncontact mapping system (Ensite 3000, Endocardial Solutions, St. Paul, Minnesota) was used to guide RFA. Virtual unipolar electrograms along the ablation line during CS pacing after RFA were analyzed. Complete or incomplete CTI block was confirmed by the activation sequence on the halo catheter and noncontact mapping. Results Three groups were classified after ablation. Group I (n = 37) had complete bidirectional CTI block. During CS pacing, the second component of unipolar electrograms showed an R or Rs pattern. Group II (n = 12) had incomplete CTI block. The second component of unipolar electrograms showed an rS pattern. Group III (n = 3) had complete CTI block with transcristal conduction. The second component of unipolar electrograms showed an rSR pattern. Conclusions A predominant R-wave pattern in the second component of unipolar double potentials at the ablation line indicates complete CTI block, even in the presence of transcristal conduction.

ObjectivesThe aim of the study was to investigate the conduction properties and anisotropy of the crista terminalis (CT) in patients with atrial flutter (AFL) using non-contact mapping.BackgroundThe CT is a posterior barrier during typical AFL. However, the CT has transverse conduction capabilities in patients with upper loop re-entry (ULR).MethodsTwenty-two patients (16 males, 63 ± 15 years) with typical AFL and ULR were included. Non-contact mapping of the right atrium during AFL and pacing from coronary sinus (CS) and low anterolateral right atrium (LARA) was performed to evaluate transverse conduction across the CT. During ULR, the longitudinal (CVL) and transverse (CVT) conduction velocity along and across the CT were measured. The width of the CT conduction gap was evaluated to guide radiofrequency ablation (RFA).ResultsNo transverse CT gap conduction was found during typical AFL. Transverse CT gap conduction was found in three patients during CS pacing and in three patients during LARA pacing. During ULR, CVLwas greater than CVT(1.28 ± 0.43 vs. 0.73 ± 0.30 m/s, p < 0.001). The CVL/CVTratio was 1.95 ± 0.77, which was inversely related to the CT gap width (15.7 ± 6.8 mm) (p < 0.001). The RFA of the CT gap was successful in 18 patients. Four patients had recurrence of arrhythmias during the follow-up of 11 ± 3 months.ConclusionsMost of the CT conduction gaps were functional and only appeared during ULR. The width of the CT gap was inversely related to the anisotropic ratio of the CT. The RFA of the CT gap was effective in eliminating ULR.

A sensitive and specific high-performance liquid chromatography (HPLC)-electrospray ionization multiple-stage mass spectrometry for the simultaneous separation and identification of 20 chemical constituents in the traditional Chinese medicinal preparation of the Shenbao tablet is established. The samples are separated with an Alltima C(18) column (250 x 4.6 mm, 5 microm) by linear gradient elution using water-acetic acid (A; 100:0.5, v/v) and acetonitrile (B; 0 min, 76:24; 15 min, 70:30; 40 min, 53:47; 50 min, 30:70; and maintain 10 min) as the mobile phase at a flow rate of 1.0 mL/min. The ion trap mass spectrometer is coupled to the HPLC system. Satisfactory results are obtained within 60 min for the simultaneous separation and identification of the 20 constituents. This is the first report on the analysis of main chemical constituents in the Shenbao tablet.

Background— This study investigated the electrophysiologic characteristics, atrial activation pattern, and effects of radiofrequency (RF) catheter ablation guided by noncontact mapping system in patients with focal atrial tachycardia (AT). Methods and Results— In 13 patients with 14 focal ATs, noncontact mapping system was used to map and guide ablation of AT. AT origins were in the crista terminalis (n=8), right atrial (RA) free wall (n=3), Koch triangle (n=1), anterior portion of RA–inferior vena cava junction (n=1), and superior portion of tricuspid annulus (n=1); breakout sites were in the crista terminalis (n=5), RA free wall (n=5), middle cavotricuspid isthmus (n=2), and RA–superior vena cava junction (n=2). ATs arose from the focal origins (11 ATs inside or at the border of low-voltage zone), with preferential conduction, breakout, and spread to the whole atrium. After applications of RF energy on the earliest activation site or the proximal portion of preferential conduction from AT origin, 13 ATs were eliminated without complication. During the follow-up period (8±5 months), 11 (91.7%) of the 12 patients with successful ablation were free of focal ATs. Conclusions— Focal AT originates from a small area and spreads out to the whole atrium through a preferential conduction. Application of RF energy guided by noncontact mapping system was effective and safe in eliminating focal AT.

In the experiment for the determination of the gravitational constant G, we found an abnormal vibrational mode of the torsion pendulum. The abnormal mode disappeared as a magnetic damper was introduced to the torsion pendulum system. Our experimental results also show that the magnetic damper can be used to suppress the high frequency vibrational noises to torsion pendulums effectively.

A non-aqueous reversed phase HPLC was developed for determining alpha-tocopherol in Sea buckthorn oil capsule without the need for saponification. A reversed phase column (Alltima C(18), 4.6 x 250 mm, 5 microm) was used with a mobile phase of methanol-acetonitrile (95 : 5, v/v) and flow rate of 1 ml/min. The contents in capsule were extracted with n-hexane. Detection wavelength was set at 292 nm. Each analysis requires no longer than 20 min. The linearity range for alpha-tocopherol was 9.4-47.0 microg/ml. The detection limit was 0.94 microg/ml. The mean recovery was 95.82 (RSD 2.3%). This method is suitable for quantitative analysis of alpha-tocopherol in Sea buckthorn oil or its Traditional Chinese Medicinal preparation.

Background: Although the reentrant circuit of typical atrial flutter (AFL) has been well recognized, the activation around the Eustachian ridge (ER) has not been fully characterized. The aim of this study was to delineate the activation patterns around the ER during typical AFL using high-resolution noncontact mapping. Methods: Fifty-three patients (M/F = 43/10, 62 ± 14 years) with typical AFL were included. The high-resolution mapping of the right atrium using a noncontact mapping system during AFL and pacing from the coronary sinus (CS) was performed to evaluate the conduction through the ER. Results: Three types of activation patterns around the ER could be classified according to the ER conduction during AFL and CS pacing. Type I (n = 21, M/F = 16/5, 61 ± 13 years) exhibited conduction block at the ER during AFL and CS pacing. The local unipolar electrograms at the ER exhibited long double potentials (DPs) (109 ± 12 ms, range 77–153 ms) during AFL and CS pacing (84 ± 18 ms, range 48–129 ms). Type II (n = 8, M/F = 7/1, 61 ± 15 years) exhibited conduction block at the ER during AFL, but conduction through the ER during CS pacing. The unipolar electrograms exhibited long DPs (119 ± 12 ms, range 97–141 ms) at the ER during the tachycardia and an rS pattern during CS pacing. Type III (n = 24, M/F = 20/4, 61 ± 16 years) exhibited an activation wavefront that passed along the ER, with the sinus venosa as the posterior barrier during AFL. During CS pacing, all cases exhibited conduction through the ER with an rS pattern. Conclusions: This study is the first to demonstrate the three patterns of activation along the ER during AFL and CS pacing. This finding suggested that the ER is an anatomic and functional barrier during typical AFL.

Atrioventricular nodal reentrant tachycardia (AVNRT) is the most common supraventricular tachycardia in adulthood. Although selective ablation of the slow AV nodal pathway can cure AVNRT, accidental AV block may occur. The details on the electrophysiologic characteristics, quantitative data on the voltage inside Koch's triangle, and the use of three-dimensional noncontact mapping to facilitate the catheter ablation of AVNRT associated with a high-risk for AV block or other arrhythmias have been limited.Nine patients (M/F=5/4, 34+/-23 years, range 17-76) with clinically documented AVNRT were included. All patients had undergone previous sessions for slow AV nodal pathway ablation but they had failed, because of repetitive episodes of complete AV block during the RF energy applications. Further, one patient had a complex anatomy and 4 patients were associated with other tachycardias, respectively. The electrophysiologic studies revealed that 4 patients had the slow-fast, 4 the slow-intermediate and one the fast-intermediate form of AVNRT. Noncontact mapping demonstrated two types of antegrade AV nodal conduction, markedly differing sites of the earliest atrial activation during retrograde VA conduction, and a lower range of voltage within Koch's triangle. The lowest border of the retrograde conduction region was defined on the map, and the application of the RF energy was delivered below that border to prevent the occurrence of AV block. The distance between the successful ablation lesions and the lowest border of the retrograde conduction region was significantly shorter in the patients with the slow-intermediate form of AVNRT than in those with the slow-fast form (5.5+/-3.4 vs. 15+/-7.6 mm; p0.05). After the ablation procedure, either rapid pacing or extrastimulation could not induce any tachycardia, and there was no recurrence during the follow-up (10.3+/-5.4, 2 to 22 months).Noncontact mapping could effectively demonstrate the antegrade and retrograde atrionodal conduction patterns, electrophysiologic characteristics of Koch's triangle, and guide the successful catheter ablation in difficult AVNRT cases.

Background— Catheter ablation of the right atrial (RA) substrate has had variable efficacy in curing paroxysmal atrial fibrillation (PAF), suggesting that RA substrate ablation can play an important role in the treatment of atrial fibrillation (AF) in some patients. The aim of this study was to investigate the electrophysiological characteristics and ablation strategy and its results in a specific group of patients with paroxysmal RA-AF. Methods and Results— The study population consisted of 13 patients (8 men; age, 64±15 years) with drug-refractory (2±1 drugs), frequent episodes of PAF. Provocation maneuvers did not reveal any ectopic beat–initiating AF. However, rapid atrial pacing easily induced AF. Activation mapping during sinus rhythm, atrial pacing, and AF was visualized by using a noncontact mapping system. Noncontact mapping revealed RA reentry (6 patients with single-loop circuits and 7 with double-loop circuits) with conduction through channels between lines of block, crista terminalis gaps, and the cavotricuspid isthmus, which could be identified during sinus rhythm and atrial pacing, resulting in fibrillatory conduction in other parts of the RA. The consistency of wavefront activation was confirmed by frequency analysis from equally distributed mapping sites in the RA. Short lines of ablation lesions were aimed at the conduction channels between the lines of block, crista terminalis gaps, and the cavotricuspid isthmus, resulting in bidirectional block. AF was eliminated in 11 (85%) of 13 patients, and those 11 patients with acute success were free of AF without any antiarrhythmic drugs during the long-term follow-up period (16±6 months). Conclusions— RA ablation still can cure selected patients with PAF. Linear ablation of the RA substrate guided by the electrophysiological characteristics of RA-AF is an effective approach for treating this specific group of patients with AF.

UNLABELLED Right atrial substrate of supraventricular tachyarrhythmias. BACKGROUND Voltage mapping has been used to detect diseased myocardium. However, accurate determination of the local atrial voltage at the same site, and simultaneous recordings from multiple mapping sites were limited. The purpose of this study was to investigate the right atrial (RA) substrate properties in patients with supraventricular tachyarrhythmias (SVT). METHODS AND RESULTS Forty patients (aged 55+/-20 years) undergoing noncontact mapping and ablation of SVT constituted the study population. There were eight patients with atrioventricular node reentrant tachycardia (AVNRT), eight patients with focal atrial tachycardia (AT), 14 patients with atrial flutter (AFL), and 10 patients with atrial fibrillation (AF). The mean peak negative voltage (PNV) was analyzed in virtual unipolar electrograms, which were obtained from 256 equally distributed RA endocardial sites during sinus rhythm (SR), atrial pacing, and tachycardia. The mean PNV of global RA during SR (-1.34+/-0.22 vs. -0.90+/-0.40 vs. -1.00+/-0.36 vs. -0.85+/-0.35 mV, P=0.04), atrial pacing at cycle lengths of 500 ms (-1.30+/-0.29 vs. -0.70+/-0.35 vs. -0.76+/-0.25 vs. -0.64+/-0.26 mV, P=0.02), and 300 ms (-1.54+/-0.47 vs. -0.94+/-0.21 vs. -0.75+/-0.27 vs. -0.57+/-0.22 mV, P

Focal Atrial Tachycardia. Introduction: Adenosine can terminate most focal atrial tachycardias (ATs). However, information about the termination mechanism is limited. This study investigated the effects and mechanism of adenosine on terminating focal AT using a three-dimensional noncontact mapping system. Methods and Results: The study consisted of 7 patients (4 men and 3 women; age 44 ′ 29 years) with focal AT. Cycle length variation and atrial activation pattern at baseline and just before AT termination by adenosine (3-12mg) were analyzed. Noncontact mapping demonstrated focal AT propagated from the origin (O) with preferential conduction and spread away from the breakout sites to the whole atrium. Compared to baseline AT, termination episodes revealed higher mean beat-to-beat variation of AT cycle length (11.7 ′ 11.7 msec vs 4.7 ′ 4.5 msec, P < 0.001) and standard deviation of normalized AT cycle length (0.033 ′ 0.014 vs 0.011 ′ 0.005, P < 0.001). In termination episodes, adenosine significantly decreased the peak negative voltage of AT-O (-27.2 ′ 15.3%, P < 0.01), preferential conduction (proximal: -32.1 ′ 18.7, mid: -28.4 ′ 22.8, distal portion: -29.6 ′ 21.4%, P < 0.01), and breakout (-31.4 ′ 12.5%, P < 0.01). However, adenosine did not affect voltage in nontermination episodes. Adenosine shifted the locations of AT-O in 5 of 10 AT episodes with termination. Mean number of shifting AT-O was 2.4 ′ 1.5 (range 1-4), with maximum shifting distance of 15.0 ′ 3.1 (range 10-19) mm. Focal activation at AT-O simply disappeared in all termination episodes and therefore was not due to conduction block within preferential conduction or breakout site. Catheter ablation lesions covered 50% of total shifting origins, without late recurrence. Conclusion: Adenosine-induced AT termination was associated with significantly decreased electrogram voltage, shifting AT-O locations, and disappearance of focal activation.

This study was performed to differentiate upper loop re-entry (ULR) from reverse typical atrial flutter (AFL).Right atrial ULR and reverse typical AFL have different mechanisms and ablation strategies, but similar electrocardiographic characteristics.This study included 26 patients with reverse typical AFL and 20 patients with ULR. The noncontact mapping system (EnSite-3000, Endocardial Solutions, St. Paul, Minnesota) was used to confirm diagnosis and guide successful radiofrequency ablation. Flutter wave polarity and amplitude in the 12-lead surface electrocardiogram were determined by two independent electrophysiologists.The flutter wave polarity in leads I and aVL was significantly different between the reverse typical AFL and ULR groups (por = 0.001). Voltage measurement revealed significant differences between reverse typical AFL and ULR in leads I, II, aVR, aVF, V1, and V2 (p0.001). A new diagnostic algorithm based on negative or isoelectric/flat flutter wave polarity and amplitudeor =0.07 mV in lead I was useful for diagnosis of ULR, with an accuracy of 90% to 97%, a sensitivity of 82% to 100%, and a specificity of 95%.Polarity and voltage measurement of flutter wave in lead I can differentiate reverse typical AFL from ULR.

Paroxysmal atrial fibrillation (PAF) can be initiated by ectopic activation from the crista terminalis. The crista terminalis conduction gap is also a critical isthmus in atrial reentrant arrhythmias like upper and lower loop reentry. The aim of this study was to investigate the mechanism and results of catheter ablation for complex atrial arrhythmias originating from the crista terminalis using the noncontact mapping system (NCM). The study population consisted of six patients (5 men, 1 woman; 70 +/- 9 years) with drug refractory PAF and typical/atypical atrial flutter. NCM identified the earliest ectopic activation originating from the crista terminalis in these six patients. The reentry circuit of atypical atrial flutter propagated around the upper crista terminalis in five patients, and lower crista terminalis in one patient. The reentry circuit of atypical atrial flutter and the initial reentry circuit of AF conducted through the crista terminalis gap in all patients. Radiofrequency applications were delivered on the sites of ectopy, which initiated AF. Substrate modification was also performed over the crista terminalis gap (six patients) and cavotricuspid isthmus (three patients) responsible for the reentry. During a mean follow-up of 9 +/- 5 months (range 5-18 months), five patients were free of AF without antiarrhythmic drugs, and one patient did not have AF or atrial flutter using propafenone. NCM demonstrated the mechanism of crista terminalis ectopy-initiating AF and associated typical/atypical atrial flutter. Catheter ablation of crista terminalis ectopy and substrate for the reentry guided by NCM successfully eliminated these atrial arrhythmias.

High plasma levels of pro-inflammatory cytokines play an important role in the pathophysiology of congestive heart failure (CHF). Therefore, we conducted a case-control study to determine the correlations between plasma levels of cytokines, i.e., tumor necrosis factor-alpha (TNF-alpha) and interleukin (IL)-6, and the severity and mortality in patients with CHF.One-hundred and 18 cases (62+/-15 years old) were classified into 3 groups: group 1 comprised 44 control cases with normal coronary arteriogram and left ventriculography and without valvular disorders or cardiomyopathy; group 2 comprised of 37 cases with mild CHF in New York Heart Association (NYHA) functional class (FC) II; group 3 had 37 cases with moderate/severe CHF in NYHA FC III or IV. Pre-catheterization plasma levels of TNF-alpha and IL-6 along with clinical and hemodynamic variables and follow-up data of cardiac death were assessed.Patients of group 3 had smaller body mass index, lower systolic and diastolic blood pressures, faster heart rates, higher left ventricular end-diastolic pressure and lowered triglyceride levels than the patients of groups 1 and 2. The plasma levels of TNF-alpha and IL-6 increased significantly in patients of group 3 in comparison with patients of groups 1 and 2 (both p0.001). Over the following 1.5 years, 13 patients died. Univariate analysis identified the following variables to be associated with poor prognosis: NYHA FC (p0.001), plasma TNF-alpha (p = 0.013), plasma IL-6 (p0.001), systolic blood pressure (p = 0.001), heart rate (p = 0.045) and left ventricular end-diastolic pressure (p = 0.021). Multivariate Cox regression analysis identified the independent predictors of cardiac death as FC (p = 0.007) and plasma IL-6 (p = 0.021).Our findings indicate that the plasma levels of IL-6 and TNF-alpha and especially the former, is a useful marker to correlate the progression of severity and late cardiac death in patients with CHF.

Introduction: Information about the activation patterns inside the superior vena cava (SVC) and entry and exit sites at the SVC-right atrial (RA) junction during SVC tachyarrhythmia is limited. Methods and Results: A detailed characterization of electrophysiologic mechanisms and ablation strategies was performed using a noncontact three-dimensional mapping system in two cases of SVC tachycardia. The first case demonstrated SVC tachycardia originating from an ectopic focus inside the SVC, with sustained depolarization and conduction to the atrium. Entry and exit sites across the SVC-RA junction were located very close to each other. The second case demonstrated two different reentrant circuits, one inside the SVC and the other into and out of the SVC-RA junction. The entry and exit sites were located far away from each other. Conclusion: Noncontact mapping may help to reveal the mechanism of SVC tachyarrhythmias and to locate entry and exit sites at the SVC-RA junction as a guide for catheter ablation.(J Cardiovasc Electrophysiol, Vol. 14, pp. 533-539, May 2003)

Catheter Ablation of Atrial Fibrillation. A 74-year-old man with atrial fibrillation (AF) underwent electrophysiologic study and catheter ablation with a noncontact mapping system. AF was induced by coronary sinus pacing, and noncontact mapping showed ever-changing movement of multiple wavefronts with one dominant reentrant circuit around the tricuspid annulus, splitting wavefront conduction through the gaps in the crista terminalis, and then fusion and stasis of wavefronts. After creation of bidirectional conduction block over crista terminalis gaps and the cavotricuspid isthmus, AF or atrial flutter was noninducible. No further AF recurrence was noted during 6-month follow-up.