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Background: Alteration in ventricular repolarization has been reported in patients with spinal cord injuries (SCIs). However, its clinical impact remains unclear. Objective: The purpose of this study was to investigate the correlation between SCIs and ventricular repolarization and the associated clinical impact. Methods: One hundred forty-four patients with an SCI were retrospectively reviewed and were divided into two groups (SCI level ≤T6, n = 110; SCI level >T6, n = 34). The electrocardiograms were reviewed during acute phase (at emergency room) and chronic phase (>1 year). Results: There were no differences in the underlying diseases or in ASIA score between the two groups, except there were more patients with tetraplegia among those with an SCI level ≤T6. For the electrophysiological parameters from the electrocardiograms, the patients with an SCI level ≤T6 had longer QTc and PR interval than those with an SCI level >T6 during acute phase. In the chronic phase, there were no differences in the electrophysiological parameters between the two groups. Only in patients with an SCI level ≤T6 did a Kaplan-Meier analysis show that QTc prolongation could predict 30-day mortality after the acute injury. After multivariate Cox regression analysis, only tetraplegia and QTc prolongation were independent predictors of 30-day mortality (odds ratios 7.85 and 34.62, respectively). In patients with an SCI level ≤T6, the QTc intervals were shorter in the chronic phase than those during the acute phase. Conclusion: QTc interval was associated with the level of acute SCI and predicted the 30-day mortality. [ABSTRACT FROM AUTHOR]

Background: Inflammation, an important mechanism in the pathogenesis of atrial fibrillation (AF), can be regulated by CD36 in monocytes.Objective: The purpose of this study was to test the hypothesis that CD36 in monocytes contributes to the pathogenesis of AF.Methods: A prospective study that enrolled 87 patients with AF and 70 without AF was conducted.Results: Compared to patients without AF, patients with AF had monocytes with a lower level of CD36 protein, which correlated with left atrial diameter, left atrial emptying fraction, and left atrial mean voltage. In AF patients after catheter ablation, Kaplan-Meier analysis showed that the sinus rhythm maintenance rate was higher in patients with high CD36 levels. Low CD36 level was an independent predictor of recurrence. After successful ablation, the CD36 level increased by 57%, reaching that of control patients. CD36 level was not correlated with the level of high-sensitivity C-reactive protein. Analysis of mRNA levels from a buffy coat revealed that AF patients had lower CD36 and interleukin-10 levels and higher peroxisome proliferator-activated receptor-γ and tumor necrosis factor-α levels, with CD36 level positively correlated with interleukin-10 level but inversely correlated with peroxisome proliferator-activated receptor-γ and tumor necrosis factor-α levels.Conclusion: Low CD36 levels in circulating monocytes were associated with AF occurrence and predicted recurrence after catheter ablation. The link between CD36 and AF identified a novel AF-related inflammatory pathway. [ABSTRACT FROM AUTHOR]

Background: Few epidemiologic data on the gender differences among patients with accessory atrioventricular pathways have been reported. Objective: The purpose of this study was to investigate the explicit gender differences in electrophysiologic characteristics among patients with accessory atrioventricular pathways. Methods: A total of 1,821 consecutive patients with accessory atrioventricular pathways were referred to our institution for electrophysiologic study and radiofrequency catheter ablation. A detailed electrophysiologic study was performed in all patients. Results: Patient age at onset of atrioventricular reentrant tachycardia was 43 ± 17 years. There were 1,117 males (61.3%) with accessory atrioventricular pathways. Men had more manifest and left-sided but fewer multiple accessory pathways. Men had more antidromic atrioventricular reentrant tachycardia. Men had a shorter anterograde accessory pathway effective refractory period (ERP) and a higher prevalence of an anterograde accessory pathway ERP (<250 ms). Men with accessory atrioventricular pathways had a longer atrioventricular nodal ERP and atrial ERP and a shorter ventricular ERP. Conclusion: Gender differences in the clinical and electrophysiologic characteristics of patients with accessory atrioventricular pathways could be closely linked and may imply a different pathogenesis. [ABSTRACT FROM AUTHOR]

Background: The regional distribution of the low-voltage zones (LVZs) may relate to the maintenance of atrial arrhythmias in the right atrium (RA). Objectives: The purpose of this study was to investigate the RA substrate characteristics in different types of atrial arrhythmias originating from RA and left atrium (LA). Methods: Forty-five patients (35 men, age = 62 ± 15 years) with RA atypical atrial flutter (n = 15, group 1), RA atrial fibrillation (AF; n = 15, no PV initiating foci, group 2), and LA AF (n = 1 5, no RA arrhythmias, group 3) referred for three-dimensional EnSite mapping were included. Voltage and activation maps were visualized. Results: The mean voltage of the RA was lower in group 2, and compared with group 3, a voltage reduction during atrial pacing was evident in groups 1 and 2. The fixed LVZs (independent of the rhythm) were mostly located along the lower crista terminalis (CT). A functional extension of the LVZ was located on the CT in 84% of patients, sinus venosa in 18%, and free-wall region in 27%, forming the borders of the slow conduction isthmus for the reentrant circuits. The number of slow conduction isthmuses was 1.3 ± 0.9, 2.2 ± 1.0, and 0.87 ± 0.74, for the groups 1–3 patients, respectively (P <.05). Radiofrequency ablation connecting the LVZs successfully eliminated those isthmuses. The long-term follow-up revealed that 66% of the patients remained in sinus rhythm. Conclusions: Single and multiple slow conduction isthmuses bordered by the fixed and functional LVZs were critical for the reentrant circuits in the RA. The conduction isthmuses could be identified by their substrate characteristics and ablated successfully. [Copyright &y& Elsevier]

Background: Termination of atrial fibrillation (AF) can be achieved by catheter ablation. It has been used as one of the procedural endpoints for AF ablation. Objective: The purpose of this study was to investigate the factors that predict AF termination and the association with long-term outcomes. Methods: Eighty-five consecutive AF patients (33 paroxysmal, 52 nonparoxysmal) underwent three-dimensional mapping and catheter ablation. A stepwise ablation approach included circumferential pulmonary vein (PV) isolation and left atrial (LA) linear ablation, followed by LA and right atrial (RA) electrogram-based (complex fractionated atrial electrogram) ablation. Clinical and electrophysiologic characteristics were assessed to evaluate the predictors of acute AF termination. Results: In univariate analysis, a diagnosis of paroxysmal AF, shorter AF history, absence of history of heart failure, smaller LA diameter, longer postablation coronary sinus cycle length, lower LA and RA mean dominant frequencies, lower RA max dominant frequency, and higher LA voltage were related to acute termination of AF during ablation. Multivariate analysis showed that smaller LA diameter and lower preablation mean RA dominant frequency were independent predictors of AF termination. Multivariate analysis also showed that larger LA diameter and the presence of RA non-PV ectopy during the index procedure could predict late recurrence during long-term (13 ± 8 months) follow-up. Conclusion: LA size and RA non-PV drivers are important for acute termination of AF and for long-term success. Careful selection of patients, extensive RA mapping, and LA ablation may enhance long-term ablation efficacy. [Copyright &y& Elsevier]

Background: Information about the electrophysiologic characteristics and long-term outcome of catheter ablation in patients with multiple focal atrial tachycardia (AT) is limited. Objective: The purpose of this study was to investigate the electrophysiologic characteristics and long-term outcome of catheter ablation in patients with multiple focal AT. Methods: Two hundred fifty-one patients who were referred for radiofrequency catheter ablation of focal AT were included for analysis. Results: Forty-four patients who had focal AT with more than one focus were identified. Comparing focal AT with a single focus to that with more than one focus, the existence of a left atrial focus, cardiovascular comorbidity, nonparoxysmal tachycardia, shortest tachycardia cycle length, success rate of the ablation, and procedure time all differed. Multivariate logistic analysis revealed that a left atrial focus, cardiovascular comorbidity, and shortest tachycardia cycle length were independent predictors of focal AT with more than one focus. Noncontact mapping of the right atrium revealed larger low-voltage zone and longer total activation time for focal AT with more than one focus. Patients who had focal AT with more than one focus and a failed ablation had a greater number of focal ATs and mechanisms of nonparoxysmal tachycardia. Multivariate logistic analysis revealed that only the number of focal ATs predicted a failed ablation. Conclusion: Focal ATs with more than one focus have different electrophysiologic characteristics. This study provides new insight into the development and atrial remodeling of focal AT with multiple foci. [Copyright &y& Elsevier]

Background: Data detailing the age-related difference in the atrial substrate for formation of typical atrial flutter (AFL) are sparse. Objective: The purpose of this study was to characterize the difference in the right atrial substrate related to aging using noncontact mapping of the right atrium. Methods: A total of 54 patients (23 young [<60 years; 45 ± 12 years] and 31 old [≥60 years; 74 ± 6 years]) with typical AFL who underwent three-dimensional noncontact mapping of typical AFL were enrolled in the study. The atrial substrate was characterized according to (1) regional wavefront activation mapping, (2) regional conduction velocity, and (3) regional voltage distribution by dynamic substrate mapping. Results: During activation mapping of the crista terminalis, two activation patterns were observed: (1) around the upper end of the crista terminalis (67%) and (2) through a gap in the crista terminalis. The presence of a crista terminalis gap was associated with a high incidence of induced atypical AFL/atrial fibrillation (P <.001). The conduction velocities of the medial cavotricuspid isthmus were slower in the old group than in the young group. In regional activation mapping of the AFL, the location of the slowest conduction shifted from the lateral cavotricuspid isthmus (71%) in the young group to the medial cavotricuspid isthmus (40%) in the old group. More cases with a low-voltage zone (≤30% peak negative voltage) extending to the medial side of the cavotricuspid isthmus occurred in the old group than in the young group (55% vs 17%, P = .012). Conclusion: The atrial substrate responsible for formation of typical AFL differed between young and old patient groups. [Copyright &y& Elsevier]

Background: Regions of rapid and multiple deflections can be identified with high dominant frequency (DF) during sinus rhythm (SR). These areas may play a role in the perpetuation of atrial fibrillation (AF) and indicate an atrial substrate abnormality. Objective: The purpose of this study was to investigate the atrial substrate properties of the high-frequency sites in patients with paroxysmal AF. Methods: Forty patients (52 ± 12 years of age) with paroxysmal AF were studied using a three-dimensional mapping system. Spectral analysis was performed on the bipolar electrograms in the left atrium (LA) during SR. Overall, 7708 electrograms were analyzed, and the DFs higher than 70 Hz were labeled as abnormal. Results: The regional distribution of the high-DF sites in the LA could be divided into two types. Type 1 includes high-DF sites existing only in the pulmonary veins (PVs; n = 19, 6.6 ± 3.4 sites/patient). Type 2 includes high-DF sites in the LA or LA plus the PVs (n = 21, 11 ± 5.6 sites/patient). In type 1, PV isolation (PVI) could eliminate the AF with negative AF inducibility testing after the PVI in 89% of patients. In type 2, additional LA substrate modification was needed in 81% of patients because sustained AF was induced after the PVI (P<.001, compared with type 1). Multivariate analysis showed that the lower mean voltage of the LA and high-frequency sites distribution both independently predicted a positive AF inducibility after the PVI (P<.05). Conclusions: Spectral analysis during SR can detect an abnormal atrial substrate. A regional distribution of the high-DF sites predicts the efficacy of the PVI. [Copyright &y& Elsevier]

Background: Temporal variation in complex fractionated atrial electrograms (CFAEs) exists during atrial fibrillation (AF). Objective: This study sought to quantify the variation in CFAEs using a fractionation interval (FI) algorithm and to define the shortest optimal recording duration required to consistently characterize the magnitude of the fractionation. Methods: Twenty-seven patients undergoing AF mapping in the left atrium were studied. The FI and frequency analysis were performed at each mapped site for recording durations of 1 to 8 seconds. The magnitude of the fractionation was quantified by the FI algorithm, which calculated the mean interval between multiple, discrete deflections during AF. The results from each duration were statistically compared with the maximal-duration recording, as a standard. The FI values were compared with the dominant frequency values obtained from the associated frequency spectra. Results: The FIs obtained from recording durations between 5 and 8 seconds had a smaller variation in the FI (P < .05) and, for those sites with a FI < 50 ms, the fractionation was typically continuous. The fast-Fourier Transform spectra obtained from the CFAE sites with recording durations of >5 seconds harbored higher dominant frequency values than those with shorter recording durations (8.1 ± 2.5 Hz vs. 6.8 ± 0.98 Hz, P < .05). The CFAE sites with continuous fractionation were located within the pulmonary veins and their ostia in 77% of patients with paroxysmal AF, and in only 29% of patients with nonparoxysmal AF (P < .05). Conclusion: The assessment of fractionated electrograms requires a recording duration of ≥5 seconds at each site to obtain a consistent fractionation. Sites with the shortest FIs consistently identified sites with the fastest electrogram activity throughout the entire left atrium and pulmonary veins. [Copyright &y& Elsevier]

Objectives: We sought to investigate the imaging of the left atrial (LA) muscular bundle and the relationship between the bundle and inducibility of tachyarrhythmia after pulmonary vein isolation (PVI). Background: Noninducibility is used as a clinical end point of atrial substrate ablation after PVI. However, little is known about the role of the LA muscular bundles in tachyarrhythmia after PVI. Methods: Forty-three consecutive patients with paroxysmal atrial fibrillation who underwent catheter ablation were included. Bi-atrial isochronal mapping was performed with the NavX system (St. Jude Medical Inc., St. Paul, Minnesota) during sinus rhythm. After 4 PVI, inducible organized LA flutter with or without transforming to atrial fibrillation (AF) (LA flutter/AF) was ablated with additional lines at the roof and/or mitral isthmus. Results: The existence of bilateral muscular bundles was an independent predictor of LA flutter/AF after PVI (p = 0.02). Patients with LA flutter/AF after PVI had a greater index of the double potentials (5.4 ± 3.4% vs. 2.8 ± 1.8%, p = 0.006) and interpotential interval (33 ± 5 ms vs. 29 ± 4 ms, p = 0.02) than without LA flutter/AF. The muscular bundles were identified in 28% patients using 16-slice multidetector computed tomography, which were identical to the isochrone map. Patients with noninducible LA flutter/AF after PVI plus the additional linear ablation had a lower recurrence rate as compared with the patients without it (19% vs. 75%, p = 0.02). Conclusions: Left atrial muscular bundles may provide a conduction block line and barrier, which is important for the formation of LA flutter/AF after PVI. The noninducibility of LA flutter/AF achieved after additional linear ablation may contribute to a better outcome in RF ablation of paroxysmal atrial fibrillation. [Copyright &y& Elsevier]

Abstract: Background: 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. Methods and results: 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; p <0.05). 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). Conclusions: 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. [Copyright &y& Elsevier]

Objectives: The purpose of this study was to investigate the relationship between the abnormal substrate and peak negative voltage (PNV) in the right atrium (RA) with atypical flutter. Background: The impact of a local abnormally low voltage electrogram on the local activation pattern and velocity of atrial flutter (AFL) remains unclear. Methods: Twelve patients with clinically documented AFL were included to undergo noncontact mapping of the RA. The atrial substrate was characterized by the: 1) activation mapping; 2) high-density voltage mapping; and 3) conduction velocity along the flutter re-entrant circuit. The normalized PNV (i.e., the relative ratio to the maximal PNV) in each virtual electrode recording was used to produce the voltage maps of the entire chamber. The protected isthmus was bordered by low voltage zones. Results: Atypical AFL of the RA was induced by atrial pacing in 12 patients, including 10 upper loop re-entry and 2 RA free wall re-entry flutter. These protected isthmuses were located near the crista terminalis. The mean width of the protected isthmus was 1.7 ± 0.3 cm and mean voltage at the isthmus was −0.91 ± 0.39 mV. The conduction velocities within these paths were significantly slower than outside the path (0.30 ± 0.18 m/s vs. 1.14 ± 0.41 m/s, respectively; p = 0.004). The ratiometric PNV of 37.6% of the maximal PNV had the best cut-off value to predict slow conduction, with a high sensitivity (92.3%) and specificity (85.7%). Conclusions: Characterization of the RA substrate in terms of the unipolar PNV is an effective predictor of the slow conduction path within the critical isthmus of the re-entrant circuit. [Copyright &y& Elsevier]

Objectives: This study sought to investigate the regional frequency distribution from multiple bi-atrial sites in different types of paroxysmal atrial fibrillation (AF). Background: A previous study showed a left atrium (LA) to right atrium (RA) frequency gradient in patients with paroxysmal AF. Methods: Forty-four patients (age = 60 ± 16, male patients = 27) with paroxysmal AF originating from the pulmonary veins (PVs) (n = 31) or superior vena cava (SVC) (n = 13) were included. Frequency analysis was performed on the intracardiac electrograms (7 s, 1 kHz/channel) recorded from PV, posterior LA, coronary sinus (CS), posterolateral RA, and SVC. The largest peak frequency was identified as the dominant frequency (DF). Results: In the PV-AF patients, there was a frequency gradient from the PV ostium to the LA, RA, and SVC (8.5 ± 3.3 Hz vs. 5.9 ± 1.1 Hz vs. 5.2 ± 0.85 Hz vs. 5.5 ± 0.48 Hz, respectively, p < 0.001). The highest DFs were mostly located at the arrhythmogenic PV ostium (58%). The DFs of the arrhythmogenic PV and PV ostium were significantly higher than those of the non-arrhythmogenic PVs and PV ostia (p < 0.05). In the SVC-AF patients, there was a frequency gradient from the SVC to the RA, LA, and PV (8.0 ± 2.4 Hz vs. 5.9 ± 1.1 Hz vs. 5.9 ± 0.7 Hz vs. 5.8 ± 0.7 Hz, respectively, p = 0.001). The highest DFs were mostly located inside the SVC (77%) instead of the SVC ostium (as compared with PV-AF patients, p = 0.035). Conclusions: The location of the highest DF depended on the arrhythmogenic PV or SVC. A frequency gradient was present between the arrhythmogenic thoracic vein and atrium in all patients. [Copyright &y& Elsevier]

Objectives: The purpose of this study was to investigate the predictor of non-pulmonary vein (PV) ectopic beats initiating paroxysmal atrial fibrillation (PAF). Background: Non-PV ectopic beats can initiate PAF in some patients and play an important role in the recurrence of PAF after PV isolation. Information on the predictors of non-PV ectopic beats initiating PAF is unknown. Methods: This study included 293 patients (215 men and 78 women, age 60 ± 14 years) with clinically documented drug-refractory PAF. Of the 94 patients with non-PV ectopic beats initiating PAF, 38 (40%) patients had superior vena cava (SVC) ectopic beats and 32 (34%) had left atrial posterior free wall (LAPFW) ectopic beats. Results: In a univariate analysis, only female gender was related to the presence of non-PV (p = 0.016) and SVC ectopic beats (p = 0.012). Right atrial enlargement (p = 0.005) and left atrial enlargement (p &#60; 0.001) were related to the presence of LAPFW ectopic beats. In a multivariate analysis, female gender (p = 0.043; odds ratio 2.00, 95% confidence interval [CI] 1.02 to 3.92) and left atrial enlargement (p = 0.007; odds ratio 2.34, 95% CI 1.27 to 4.32) could predict the presence of non-PV ectopic beats. Subgroup analysis showed that female gender could predict the presence of SVC ectopic beats (p = 0.039; odds ratio 2.14, 95% CI 1.04 to 4.43). In contrast, left atrial enlargement could predict the presence of LAPFW ectopic beats (p = 0.002; odds ratio 3.89, 95% CI 1.62 to 9.38). Conclusions: The location of non-PV ectopic beats initiating PAF can be predicted by both gender and left atrial enlargement. [Copyright &y& Elsevier]

Objectives: This study was performed to differentiate upper loop re-entry (ULR) from reverse typical atrial flutter (AFL). Background: Right atrial ULR and reverse typical AFL have different mechanisms and ablation strategies, but similar electrocardiographic characteristics. Methods: 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. Results: The flutter wave polarity in leads I and aVL was significantly different between the reverse typical AFL and ULR groups (p ≤ 0.001). Voltage measurement revealed significant differences between reverse typical AFL and ULR in leads I, II, aVR, aVF, V1, and V2 (p &#60; 0.001). A new diagnostic algorithm based on negative or isoelectric/flat flutter wave polarity and amplitude ≤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%. Conclusions: Polarity and voltage measurement of flutter wave in lead I can differentiate reverse typical AFL from ULR. [Copyright &y& Elsevier]

This study was aimed at evaluating the efficacy of non-contact mapping and ablation of non-incisional atypical right atrial (RA) flutters.The majority of atypical RA flutters were reported in patients after surgical incision of the RA.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.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.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. [Copyright &y& Elsevier]

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. [Copyright &y& Elsevier]

: 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, CVL was greater than CVT (1.28 ± 0.43 vs. 0.73 ± 0.30 m/s, p < 0.001). The CVL/CVT ratio 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. [Copyright &y& Elsevier]

: ObjectivesThis study was aimed at delineating the reentrant circuit of right atrial (RA) upper loop re-entry using noncontact three-dimensional mapping.: BackgroundVarious forms of atypical atrial flutter including lower loop re-entry and left atrial flutter have been demonstrated. However, little is known about upper loop re-entry in the RA.: MethodsThe study population consisted of eight patients (65 ± 12 years, seven men) with atypical atrial flutter. Right atrial activation during atrial flutter was visualized using a noncontact mapping system (EnSite-3000 with Clarity Software, St. Paul, Minnesota) for a three-dimensional reconstruction of the endocardial depolarization. The narrowest part of the re-entrant circuit was targeted using radiofrequency catheter ablation.: ResultsNoncontact mapping showed macro–re-entry confined to the RA free wall with RA activation time accounting for 100% of the cycle length (214 ± 21 ms) in all eight patients. Two patients had counterclockwise activation, and six patients had clockwise activation around the central obstacle, which was composed of the crista terminalis, the area of functional block, and superior vena cava. The lower turn-around points were located at the conduction gap in the crista terminalis. Radiofrequency linear ablation of the conduction gap in the crista terminalis was performed and eliminated atrial flutter in six patients without recurrence during a follow-up of 3.2 ± 1.1 months.: ConclusionsAtypical atrial flutter could arise from upper loop re-entry in the RA with conduction through the gap in the crista terminalis. Radiofrequency linear ablation of the conduction gap was effective in eliminating this atrial arrhythmia. [Copyright &y& Elsevier]

Examines whether alteration in beta-adrenergic and vagal activity might affect the dose of the exogenously injected adenosine required for termination of supraventricular tachycardia. Effects of adenosine under beta-adrenergic stimulation with isoproterenol; Effects of adenosine under muscarinic blockade with atropine.