Occluding morphologically complicated left atrial appendage using the small-umbrella LAmbre device.

BACKGROUND: Percutaneous left atrial appendage (LAA) occlusion is effective for stroke prevention in patients with atrial fibrillation. LAA can have a complex anatomy, such as multiple lobes or a large orifice, which may render it unsuitable for occlusion using regular devices. We aimed to investigate the feasibility, safety, and short-term efficacy of the small-umbrella LAmbre device for morphologically complicated LAA. METHODS: We retrospectively enrolled 129 consecutive patients who underwent LAA occlusion using the LAmbre device; the small-umbrella LAmbre device was used in 30 of these patients. We analyzed patients' characteristics, procedural details, and outcomes. RESULTS: Twenty-two patients (73.3%) had multilobed (≥ 2) LAA. The umbrella of the occluder was anchored in the branch in 9 patients and in the common trunks of branches in 13 patients. The landing zone and orifice diameters were 19.0 ± 4.39 mm and 27.4 ± 3.95 mm, respectively. The sizes of the umbrella and occluder cover were 22.0 ± 3.42 mm and 34.3 ± 2.75 mm, respectively. At 3-month follow-up transesophageal echocardiography in 24 patients, no peri-device residual flow was reported. Device thrombosis was detected in one patient at 3 months and disappeared after 3 months of anticoagulation. Ischemic stroke occurred in one patient; no other adverse events were reported. CONCLUSIONS: Occlusion of morphologically complicated LAA using the small-umbrella LAmbre device was feasible, safe, and effective in patients with atrial fibrillation in this study. This occluder provides an alternative for patients who cannot be treated with regular-sized LAA occlusion devices.

Multiple Intercostal Space Electrocardiogram Allows Accurate Localization of Outflow Tract Ventricular Arrhythmia Origin.

BACKGROUND: Multiple intercostal recordings were supposed to get a more comprehensive view of the depolarization vector of the outflow tract ventricular arrhythmia (OT-VA), which may help to identify the OT-VA more accurately. This study was undertaken to develop a more accurate electrocardiogram (ECG) criterion for differentiating between left and right OT-VA origins. METHODS: We studied OT-VA with a left bundle branch block pattern and inferior axis QRS morphology in 47 patients with successful catheter ablation in the right ventricular OT (RVOT; n = 37) or aortic coronary cusp (ACC; n = 10). Superior and inferior precordial leads were taken together with the routine 12-lead ECG. The ECG during the OT-VA and during sinus beats were analyzed. Transition ratio, transition zone (TZ) index, R/S amplitude ratio, and R-wave duration ratio were measured in the regular, superior, and inferior precordial leads. RESULTS: The combined TZ index, TZ index inferior was significantly smaller, while the V2 inferior transition ratio was significantly larger for ACC origins than RVOT origins (P < 0.05). The area under the curve for the combined TZ index by a receiver operating characteristic analysis was 0.974, which was significantly larger than other parameters. A cutoff value ≤0.25 predicted an ACC origin with 94% sensitivity and 100% specificity. This advantage of the parameter over others also held true for a subanalysis of OT-VAs with a lead V3 precordial transition or TZ index = 0. CONCLUSIONS: The combined TZ index outperformed other ECG criteria to differentiate left from right OT-VA origins.

Incidence of ischemic stroke and systemic embolism in patients with hypertrophic cardiomyopathy, nonvalvular atrial fibrillation, CHA2DS2-VASc score of ≤1 and without anticoagulant therapy.

Data on the risk of ischemic stroke and systemic embolism (iSSE) events in patients with nonvalvular atrial fibrillation (NVAF), a CHA2DS2-VASc score of ≤1, hypertrophic cardiomyopathy (HCM), and without anticoagulant therapy are still lacking. The aim of this study was to investigate the incidence of iSSE events in these patients. We consecutively screened medical records of patients with HCM and NVAF referred to Fuwai Hospital between January 1994 and March 2014. The primary end point was iSSE events, defined as a composite of ischemic stroke and systemic embolism. Follow-up was carried out to ascertain end point status. Medical records of 522 patients with NVAF and HCM were screened. A total of 108 patients (20.7 %) with a CHA2DS2-VASc score of ≤1 and without anticoagulant therapy were enrolled and constituted our study population. After a median follow-up of 2.4 years (range 0.6-14.1 years; 376.2 patient-years), ischemic stroke occurred in 2 patients, resulting in death of 1 patient in the first year and paralysis of the other patient in the fourth year. No other iSSE events occurred. The incidence of iSSE was 0.9 % [95 % confidence interval (CI) 0.0-5.0 %] in the first year, and 0.5 % per 100 patient-years (95 % CI 0.1-1.9 %). The risk of iSSE events seems low in patients with NVAF, a CHA2DS2-VASc score of ≤1, HCM, and without anticoagulant therapy. Multicenter studies with sizeable study populations are needed to validate the risk of iSSE events in these patients.

Effect of fat pad ablation on the spatial and temporal stability of complex fractionated atrial electrogram in acetylcholine-induced atrial fibrillation.

OBJECTIVE: The objective of this study was to investigate the effect of selective fat pad ablation on the spatial and temporal stability of the complex fractionated atrial electrogram (CFAE) in acetylcholine (ACh)-induced atrial fibrillation (AF). METHODS AND RESULTS: ACh was applied to fat pads in 10 dogs. Effective refractory periods (ERPs) at 5 different sites, AF inducibility and AF duration were obtained before and after fat pad ablation. During the first two induced AFs, the number of sites with continuous CFAEs and the duration of continuous CFAEs at every site were measured before and after fat pad ablation. The average ERP was shortened by ACh application (138 14 vs 100 15 ms, P < 0.001) and increased after fat pad ablation (100 +/- 15 vs. 115 +/- 14 ms, P < 0.001). AF inducibility (76 +/- 9% vs. 4 +/- 6%, P < 0.001) and AF duration (56 +/- 11 vs. 187 +/- 56 s, P = 0.01) increased after ACh application compared to baseline; while fat pad ablation reduced AF inducibility (76% +/- 9% vs. 54% +/- 6%, P < 0.001) and AF duration (187 +/- 56 vs. 144% +/- 35 s, P = 0.015). The percentage of sites with continuous CFAE decreased after fat pad ablation compared with that before fat pad ablation (24% vs. 82%, P < 0.001). On average, fat pad ablation reduced the duration of continuous CFAEs (188 +/- 63 vs. 139 +/- 31 s, P < 0.001). CONCLUSION: Selective fat pad ablation can affect the spatial and temporal stability of CFAEs in ACh-induced atrial fibrillation in dogs.

High-sensitivity C-reactive protein as a predictor of atrial fibrillation recurrence after primary circumferential pulmonary vein isolation.

BACKGROUND: Atrial fibrillation (AF) recurrence after circumferential pulmonary vein isolation (CPVI) is difficult to predict. Inflammation is associated with the development of AF. Inflammatory markers, such as high sensitivity C-reactive protein (hsCRP), are related to AF development via atrial remodeling. However, it is unknown whether plasma hsCRP concentration before CPVI can be used as a predictor for AF recurrence. METHODS: A total of 121 patients without structural heart disease who underwent primary CPVI by a single operator were included in the study (paroxysmal/persistent AF: 77/44). Left atrial diameter was measured by transesophageal echocardiography. Plasma hsCRP concentration was determined by enzyme-linked immunosorbent assay. Based on the follow-up outcomes, patients were divided into two groups, a recurrence group and a nonrecurrence group. AF recurrence was defined as AF or atrial flutter or atrial tachycardia episodes lasting for ≥30 s during regular follow-up (>12 months). RESULTS: A total of 36 (29.8%) patients (paroxysmal/persistent AF: 19 [24.7%]/17 [38.6%]) had AF recurrence in a mean 23 (range, 12-44) month follow-up period. The plasma hsCRP concentration in the recurrence group was significantly higher than that in the nonrecurrence group for all patients (median [quartile range] 2.22 [1.97] mg/L vs 0.89 [1.30] mg/L, P < 0.001), for patients with paroxysmal AF (2.12 [2.78] mg/L vs 0.84 [1.15] mg/L, P = 0.028), and for those with persistent AF (2.29 [1.08] mg/L vs 0.89 [1.53] mg/L, P = 0.005). Multiple logistic regression analyses showed that the higher level of the plasma hsCRP (P < 0.001) was a significant prognostic predictor of AF recurrence, both for patients with paroxysmal AF (P = 0.012) and those with persistent AF (P = 0.003). CONCLUSION: Plasma hsCRP concentration before CPVI was associated with AF recurrence after primary CPVI procedure for both paroxysmal and persistent AF patients. Plasma hsCRP concentration could play a role in prediction of AF recurrence after primary CPVI.

[Timing of positive head-up tilt test for patients with suspected vasovagal syncope].

OBJECTIVE: To investigate the time course of positive head-up tilt test (HUTT) for patients with suspected vasovagal syncope. METHODS: Consecutive patients referred to the syncope unit of our center for recurrent unexplained syncope were included. The HUTT consisted of a 30 minute passive basic phase and a 20 minute sublingual nitroglycerin provocation phase if syncope did not develop during the passive phase. RESULTS: Positive HUTT was observed in 427 out of 773 consecutive patients (55.2%) patients including 43 patients (10.1%) during the passive basic phase and 384 patients (89.9%) during the nitroglycerin provocation phase. During the basic phase, the positive Hutt developed at 7.5 minute (n = 2) and peaked at 22.5th minute (20.9%, n = 9) and then decreased gradually. Most positive reactions (93.0%, n = 40) occurred between the 10 and 25 minutes during the basic phase. During the nitroglycerin provocation phase, the percentage of positive reactions increased rapidly after sublingual nitroglycerin, peaked at the 10th minute (35.7%, n = 137) and decreased thereafter. Most positive reactions (96.1%, n = 369) occurred within the first 15 minutes of provocation phase. CONCLUSION: The appropriate duration for HUTT test could be modified to a 25 minutes passive basic phase plus 15 minutes nitroglycerin provocation phase.

The influence of metabolic syndrome on atrial fibrillation recurrence: five-year outcomes after a single cryoballoon ablation procedure.

BACKGROUND: Metabolic syndrome (MetS) has been reported as a risk factor of atrial fibrillation (AF) recurrence after radiofrequency catheter ablation. This study aimed to investigate the long-term influence of MetS on paroxysmal AF recurrence after a single cryoballoon ablation procedure, which was scarcely investigated yet in Chinese population. METHODS: In total, 137 paroxysmal AF patients who had successfully completed a single cryoballoon ablation procedure at Fuwai Hospital, Beijing, China from December 2013 to October 2015 were enrolled. Excepting for patients with AF recurrence, all patients were followed up for no less than five years. Independent predictors of AF recurrence were determined by Cox proportional hazards regression analysis. RESULTS: Among 137 paroxysmal AF patients, 91 patients (66.4%) had successfully achieved overall five-year follow-up after a single cryoballoon ablation procedure, and 44 patients (32.1%) had MetS. Patients with MetS had a significant lower incidence of freedom from AF recurrence than those without MetS (50.0% vs. 74.2%, log-rank P < 0.01) during the five-year follow-up. MetS (HR = 1.95, 95% CI: 1.069-3.551, P = 0.030) was an independent predictor of AF recurrence after adjusting for multiple factors. After the second year post cryoballoon ablation procedure, the recurrence rate of AF gradually increased in patients with MetS, in contrast, decreased recurrence rate of AF in patients without MetS. CONCLUSIONS: MetS is an independent predictor for five-year AF recurrence after a single cryoballoon ablation procedure in paroxysmal AF patients. Combination therapy of AF and MetS may improve the long-term outcomes of AF patients.

Characteristics and Long-Term Ablation Outcomes of Supraventricular Arrhythmias in Hypertrophic Cardiomyopathy: A 10-Year, Single-Center Experience.

Background: A variety of supraventricular arrhythmias (SVAs) may occur in patients with hypertrophic cardiomyopathy (HCM). The characteristics and long-term ablation outcomes of different types of SVAs in HCM have not been comprehensively investigated. Methods: We retrospectively enrolled 101 consecutive patients with HCM who were referred to the electrophysiology and arrhythmia service from May 2010 to October 2020. The clinical features and ablation outcomes were analyzed. Results: Seventy-eight patients had SVAs, which comprised 50 (64.1%) cases of atrial fibrillation (AF), 16 (20.5%) of atrial flutter (AFL), 15 (19.2%) of atrioventricular reentrant tachycardia (AVRT), 11 (14.1%) of atrial arrhythmia (AT), and 3 (3.8%) of atrioventricular nodal reentrant tachycardia (AVNRT). Thirty-four patients underwent catheter ablation and were followed up for a median (interquartile range) of 58.5 (82.9) months. There was no recurrence in patients with non-AF SVAs. In patients with AF, the 1- and 7-year AF-free survival rates were 87.5 and 49.5%, respectively. A receiver operator characteristic analysis showed that a greater left ventricular end-diastolic dimension (LVEDD) was associated with a higher recurrence of AF, with an optimum cutoff value of 47 mm (c-statistic = 0.91, p = 0.011, sensitivity = 1.00, specificity = 0.82). In Kaplan-Meier analysis, patients with a LVEDD ≥ 47 mm had worse AF-free survival than those with a LVEDD <47 mm (log-rank p = 0.014). Conclusions: In this unique population of HCM, AF was the most common SVA, followed in order by AFL, AVRT, AT, and AVNRT. The long-term catheter ablation outcome for non-AF SVAs in HCM is satisfactory. A greater LVEDD predicts AF recurrence after catheter ablation in patients with HCM.

The value of transtelephonic electrocardiogram monitoring system during the "Blanking Period" after ablation of atrial fibrillation.

OBJECTIVE: The aim of our study was to investigate the value of the transtelephonic electrocardiogram (TTECG) monitoring system during a "blanking period" of 3 months after ablation by analyzing the frequency of atrial arrhythmias episodes and the relationship between the frequency of atrial fibrillation (AF) attacks and long-term follow-up outcomes. METHODS: Ninety-two patients with AF received primary ablation and were fitted with an external loop recorder for daily and symptomatic patient-triggered detection of AF recurrence during a "blanking period," which was defined as 3 months after discharge. All patients received regularly scheduled clinical follow-up programs that included 24-hour Holter for 12 months. Atrial fibrillation recurrence was defined as an episode of AF, atrial flutter, or atrial tachycardia lasting for 30 seconds or longer, which was documented on TTECG or 24-hour Holter. After the 12th month of monitoring, patients were divided into 2 groups based on the follow-up data: a recurrence group and a nonrecurrence group. RESULTS: A total of 18 969 TTECGs were received, the rate of effective TTECGs was 96.1% (18 236/18 969). At the end of the blanking period, 39 (42.4%) patients with AF recurrence were recorded by TTECG monitoring, whereas 27 (29.3%) patients were recorded by electrocardiogram and 24-hour Holter monitoring (P = .032). By analyzing the TTECG diagnosis, the percentage of total AF attacks in the recurrence group was higher than in the nonrecurrence group (median: 27.8% versus 10.6%, P < .01). The percentage of monthly AF attacks in the recurrence group occurred at a high level during the blanking period (sequent: 24.4%, 32.4%, and 28.1%; P = .65). There was also a certain amount of AF attacks in the nonrecurrence group during the blanking period, but the percentage of AF attacks in this group significantly decreased each month (sequent: 18.6%, 11.0%, and 4.9%; P < .01). CONCLUSION: The TTECG monitoring was superior to the standard electrocardiogram and 24-hour Holter recordings in evaluating AF recurrence after ablation. Atrial arrhythmias episodes were common during the blanking period whether the long-term follow-up outcome was a success or a failure. Atrial fibrillation attacks during the blanking period did not indicate failure of ablation in long-term outcomes. However, frequent and nonsignificantly decreasing AF attacks during the blanking period indicated a high probability of failure of AF ablation in long-term follow-up outcomes.

Catheter ablation of premature ventricular complexes associated with false tendons: A case report.

BACKGROUND: False tendon is a common intraventricular anatomical variation. It refers to a fibroid or fibromuscular structure that exists in the ventricle besides the normal connection of papillary muscle and mitral or tricuspid valve. A large number of clinical studies have suggested that there is a significant correlation between false tendons and premature ventricular complexes. However, few studies have verified this correlation during radiofrequency catheter ablation of premature ventricular complexes. CASE SUMMARY: A 45-year-old male was admitted to receive radiofrequency ablation for symptomatic premature ventricular complexes. A three-dimensional model of the left ventricle was established by intracardiac echocardiography using the CartoSoundTM mapping system. In addition to the left anterior papillary muscle, the posterior papillary muscle was mapped. False tendons were found at the base of the interventricular septum, and the other end was connected to the left ventricular free wall near the apex. An irrigated touch force catheter was advanced into the left ventricle via the retrograde approach. The earliest activation site was marked at the interventricular septum attachment of the false tendons and was successfully ablated. CONCLUSION: This case verified that false tendons can cause premature ventricular complexes and may be cured by radiofrequency ablation guided by intracardiac echocardiography with the CartoSoundTM system.

Inflammation in lone atrial fibrillation.

OBJECTIVES: This study was designed to evaluate the correlation between lone atrial fibrillation and inflammation. METHODS: A total of 411 subjects were enrolled in this study, including 333 patients with lone atrial fibrillation, and 78 controls. C-reactive protein (CRP) and echocardiography were evaluated, and the electrocardiograph was monitored to identify cardiac rhythm at the time of blood sampling. According to the rhythm, paroxysmal atrial fibrillation was divided into presence and absence of atrial fibrillation. RESULTS: Subjects with lone atrial fibrillation had higher CRP levels than controls (media, 1.00 mg/L; IQR, 1.00-2.54 versus media, 1.00 mg/L; IQR, 1.00-1.55; p = 0.016) and subjects with persistent atrial fibrillation had higher CRP levels than those with paroxysmal atrial fibrillation (media, 1.62 mg/L; IQR, 1.00-3.98 versus media, 1.00 mg/L, IQR, 1.00-2.10; p = 0.022), and so did presence of atrial fibrillation rather than absence of atrial fibrillation (media, 2.11 mg/L; IQR, 1.00-3.60 versus media, 1.00 mg/L; IQR, 1.00-1.76; p = 0.000) in paroxysmal atrial fibrillation. However, there was no significant difference in CRP levels between persistent atrial fibrillation and presence of atrial fibrillation in paroxysmal atrial fibrillation (p = 0.992). Neither was there any difference between absence of atrial fibrillation in paroxysmal atrial fibrillation and controls (p = 0.483). In patients with lone atrial fibrillation, atrial fibrillation rhythm (B = 4.85, 95%CI: 2.61-8.99) was the only independent predictor of elevated CRP levels after adjusted covariants. CONCLUSIONS: Patients with lone atrial fibrillation had elevated CRP levels only when they were in atrial fibrillation rhythm and an elevated CRP level was not related to duration of time or history of atrial fibrillation.

The morphology changes in limb leads after ablation of verapamil-sensitive idiopathic left ventricular tachycardia and their correlation with recurrence.

OBJECTIVES: This study was designed to explore the morphology changes in limb leads of ECGs after successful ablation of verapamil sensitive idiopathic left ventricular tachycardia (ILVT) and their correlation with tachycardia recurrence. METHODS: Between January 2001 and December 2006, 116 patients who underwent successful ablation of ILVT were included in the study. Twelve-lead surface ECG recordings during sinus rhythm were obtained in all patients before and after ablation to compare morphology changes in limb leads. RESULTS: The ECG morphology changes after ablation were divided into two categories: one with new or deepening Q wave in inferior leads and/or disappearance of Q wave in leads I and aVL, and the other without change. The changes in any Lead II, III, or aVF after ablation occurred significantly more in patients without recurrence of ventricular tachycardia (VT) (P < 0.0001, 0.002, and 0.0001, respectively). The patients with recurrence of VT tended to have no ECG changes, compared with those without recurrence of VT (P = 0.009). The sensitivity of leads II, III, and aVF changes in predicting nonrecurrence VT were 66.7%, 78.7%, and 79.6%, specificity were 100%, 75%, and 87.5%, and nonrecurrence predictive value of 100%, 97.7%, and 98.9%, respectively. When inferior leads changes were combined, they could predict all nonrecurrence patients with 100% specificity. CONCLUSIONS: Successful radiofrequency ablation of ILVT could result in morphology changes in limb leads of ECG, especially in inferior leads. The combined changes in inferior leads can be used as an effective endpoint in ablation of this ILVT.

Radiofrequency catheter ablation of permanent atrial fibrillation under guidance of carto-merge technique.

OBJECTIVE: To investigate the feasibility and effectiveness of radiofrequency catheter ablation (RFCA) to treat per-manent atrial fibrillation (AF) under the guidance of Carto-Merge technique. METHODS: Fifteen male patients with permanent AF underwent RFCA under the guidance of Carto-Merge technique. The mean age was 54.00 +/- 10.44 years, and duration of AF was 23.66 +/- 14.93 months. Cardiac magnetic resonance angiography (MRA) was performed to obtain pre-procedural three-dimensional (3D) images on the anatomy of left atrium (LA) and pulmonary veins (PVs) before RFCA procedure. Then the electroanatomical map was integrated with 3D images of MRA to form Carto-Merge map that guided step-by-step ablation strategy of permanent AF. Circumferential PV ablation was performed first until complete PVs electric isolation confirmed by Lasso catheter. If AF was not terminated, lesion lines on roof of LA, mitral isthmus, and tricuspid isthmus were produced. RESULTS: The episodes of AF were terminated during RFCA in 2 patients, by direct current cardioversion in the remaining 13 patients. Transient AF occurred in 2 patients after ablation on 1st day and 1st week respectively, AF terminated spontaneously not long after taking metoprolol. One patient developed persistent atrial flutter (AFL) in 2 months after procedure and AFL was eliminated by the second ablation. Persistent AF recurred on 1st day, 1st and 5th week respectively in 3 patients, and did not terminate after 3 months even though amiodarone was given. The remaining 12 patients were all free of AF during 2-11 months of follow-up. The recent success rate for RFCA of permanent AF was 80%. CONCLUSIONS: Carto-Merge technique can effectively guide RFCA of permanent AF. When combined with single Lasso mapping, it can simplify the mapping, lower expenses, and enhance the success rate of RFCA of permanent AF.

[Radiofrequency catheter ablation of permanent atrial fibrillation under guidance of Carto merge technique].

OBJECTIVE: To investigate the effectiveness and advantages of the Carto merge technique in guiding radiofrequency catheter ablation (RFCA) of permanent atrial fibrillation (AF). METHODS: A total of 15 patients with permanent AF underwent RFCA under guidance of the Carto merge technique. The virtual electroanatomical map of the left atrium (LA) and pulmonary veins (PVs) were reconstructed with Carto system during the procedure. Then the electroanatomical map was integrated with 3-D images of cardiac magnetic resonance angiography to form Carto merge map. Circumferential pulmonary vein ablation was performed first until complete PVs electric isolation confirmed by lasso catheter. If AF was not terminated, lesion lines on roof of LA, mitral isthmus, and tricuspid isthmus were produced. Finally direct current (DC) cardioversion were given if sinus rhythm did not return. RESULTS: AF were terminated spontaneously during RFCA in 2 patients, and by DC cardioversion in the remaining 13 patients. Persistent AF recurred on 24 hours, first week, and 5th week, respectively in three patients. The remaining 12 patients were all free of AF during follow-up (1-10 months). The success rate was 80% in the study. CONCLUSIONS: Carto merge technique can effectively guide RFCA of permanent AF. When combined with single Lasso mapping, it can simplify the mapping and enhance the success rate of RFCA of permanent AF.

[Clinical and ECG features of arrhythmogenic right ventricular cardiomyopathy: a retrospective analysis of 31 cases].

OBJECTIVE: To retrospectively analyze the clinical and electrocardiographic features of patients with arrhythmogenic right ventricular cardiomyopathy (ARVC). METHODS: The clinical, electrocardiographic features and the efficacy of various therapies were analyzed in 31 patients (27 males) diagnosed as ARVC according to the criteria established by European Society of Cardiology. RESULTS: The averaged age when the ARVC was first diagnosed was (34.7 +/- 9.4) years (19 - 58 years), palpitation was present in 28 patients (90.3%) and syncope in 13 patients (41.9%), a family history of sudden death was present in 1 patient. Dilatated right ventricle was documented in 29 patients by echocardiography and (or) magnetic resonance imaging (MRI), 2 of them with dilated left ventricles. ECG changes included: T wave inversion, mostly seen in precordial leads (100%); epsilon (epsilon) wave (54.8%); QRS duration >or= 110 ms in V(1) to V(3) (83.9%); reduced extremity amplitude (41.9%); the first degree of AV block (22.6%); sustained VT (100%) including 15 monomorphic VT (48.4%) and 16 polymorphic VT (51.6%). The mean values of QRS duration in leads of V(1 - 3) [(120.8 +/- 13.7) ms] was significantly longer than that in V(4 - 6) [(99.4 +/- 13.7) ms, P < 0.05]. Fourteen patients underwent radiofrequency catheter ablation (RFCA) with an immediate success rate of 78.6% (11/14). During follow up (18.3 +/- 10.2) months, VT reoccurred in 6 patients (54.5%). The remaining 17 patients were treated with conventional medications, 7 of them were medicated under implanted cardioverter defibrillator (ICD). During the follow-up (35.6 +/- 19.0) months, VT reoccurred in 11 patients (64.7%) and one patient died suddenly. CONCLUSIONS: ARVC patients developed symptoms at mid-30s with significant ECG changes including appearance of an epsilon wave, T wave inversion and QRS duration >or= 110 ms in leads of V(1 - 3). The long term therapy efficacy was not satisfactory both for RFCA and conventional medications and ICD implantation should be recommended to patients with ARVC.

Left posterior fascicular block: a new endpoint of ablation for verapamil-sensitive idiopathic ventricular tachycardia.

BACKGROUND: Verapamil-sensitive, idiopathic left ventricular tachycardia (ILVT) with right bundle branch block configuration and left-axis deviation is known to be due to re-entry mechanism but the exact nature of reentrant circuit in ILVT is not fully elucidated. Radiofrequency (RF) ablation was applied during ventricular tachycardia (VT) and termination of the VT or abolishing the inducibility of the tachycardia was used as an endpoint for successful RF. In this study, the left posterior fascicular block in surface electrocardiogram (ECG) was used as a new endpoint of ablation to cure ILVT. METHODS: Electrophysiological studies and radiofrequency ablation were performed in 39 consecutive patients [30 men, 9 women; age ranging from 10 to 64 years, mean (29 +/- 16) years] with verapamil-sensitive ILVT and structurally normal hearts. VT could be terminated by the intravenous administration of verapamil in all patients. The target site was the midseptum of LV where the earliest Purkinje potentials were recorded during VT. RF current was applied to the target site with or without late diastolic potential (LDP) during sinus rhythm in 37 patients and during VT in 2 patients to meet the ablation endpoint: the left posterior fascicular block in the surface ECG. RESULTS: Thirty-seven patients with ILVT had been treated by RF ablation during sinus rhythm and two had been treated during VT. All of them met the endpoint of the left posterior fascicular block. Thirty-eight cases were symptom-free without medications during the follow-up period (range from 3 to 95 months, median 17 months). One patient developed a clinical recurrence and the left posterior fascicular block in surface ECG disappeared. The patient received another treatment. The endpoint was met and the procedure was successful. CONCLUSIONS: The left posterior fascicular block in surface ECG used as an endpoint of RF ablation to treat ILVT is effective. It is important especially in those patients whose VT can not be induced or the inducible condition is unstable. The effective endpoint implied that the left posterior fascicle might be a critical part of the re-entrant circuit.

The automaticity of Mahaim fibre and its response to effective ablation.

BACKGROUND: Typical accessory pathways (APs) of Wolf-Parkinson-White syndrome have been widely discussed in recent decades. However, the characteristics of the special AP, Mahaim fibre, are not so clear. It is known that these fibres have antegrade conduction only, long conduction time, decremental node-like conduction and automaticity properties. This study was to elucidate the automaticity of Mahaim fibre and its response to effective ablation. METHODS: Thirteen patients with Mahaim fibre (ten atrioventricular and three atriofascicular accessory pathways) were subjected to electrophysiological study and radiofrequency ablation via catheter. The incidence and characteristics of anautomatic rhythm originating from Mahaim fibre were observed during the whole procedure, especially during radiofrequency current delivery. RESULTS: Repetitive and short-run automatic rhythm (rate: 65-72 beats per minute), with a QRS morphology similar to that of clinical pre-excited atrioventricular re-entrant tachycardia (AVRT), occurred in two patients during sinus rhythm. Conduction via Mahaim fibre was successfully eliminated by radiofrequency current. Fourteen applications of RF were associated with irregularly accelerated automatic tachycardia of Mahaim fibre (with a sensitivity of 78%), lasting for 1.2-14 seconds. However, such automatic tachycardia of Mahaim fibre did not occur during 54 failed applications of radiofrequency current. CONCLUSIONS: Mahaim fibre has the function of automaticity. The accelerated automatic tachycardia of Mahaim fibre occur red during radiofrequency catheter ablation can be used as a predictor for successful procedure.

Different properties of complex fractionated atrial electrograms during atrial fibrillation.

AIMS: The aim of the present study was to investigate various properties of complex fractionated atrial electrograms (CFAEs) in different models of atrial fibrillation. METHODS: Fifteen dogs were divided into three groups (five dogs/group): group 1 (pacing-induced atrial fibrillation group), group 2 (100 mM Ach-induced atrial fibrillation group), group 3 (500 mM Ach-induced atrial fibrillation group). Five sites from the left atrium in each dog were used as recording sites. Electric stimulations were used to induce atrial fibrillation. Effective refractory period (ERP) of each recording site and atrial fibrillation inducibility index were obtained at baseline and following sustained atrial tachypacing for 4 h (group 1) or acetylcholine (Ach) application (groups 2 and 3). During the first induced atrial fibrillation, recording sites with CFAEs were identified and domain frequency of CFAE was obtained. RESULTS: ERPs decreased significantly compared to baseline in all groups (P < 0.001). There was no significant difference in decrements of ERPs at each site after pacing in group 1 (P = 0.646); in groups 2 and 3, significant differences were found in decrements of ERPs following Ach application when each site was compared (P < 0.05). Atrial fibrillation inducibility index increased in all groups compared to baseline (P < 0.05). During the first induced atrial fibrillation, CFAEs were recorded at all sites. There was no significant difference of domain frequencies in group 1 when each site was compared (P = 0.509), but significant differences in domain frequencies were found in groups 2 and 3 when each site was compared (P < 0.05). CONCLUSION: We identified that various characteristics of CFAEs may exist in different experimental models of atrial fibrillation. This may indicate different mechanisms of CFAEs.

Single dose of ibutilide for conversion of persistent atrial fibrillation after radiofrequency ablation.

BACKGROUND: Patients with persistent or permanent atrial fibrillation (AF) often need direct current cardioversion after radiofrequency ablation. The aim of this study was to investigate the effectiveness and safety of ibutilide for cardioversion of persistent or permanent atrial fibrillation after radiofrequency ablation and the factors related to conversion. METHODS: Patients with persistent or permanent atrial fibrillation were treated with combined ablation strategy including circumferential pulmonary vein isolation, linear ablation and CAFÉ potential ablation. If AF was not terminated after ablation, ibutilide was used for cardioversion (1 mg, intravenous injection in 10 minutes). These patients were divided into a conversion group and a non-conversion group according to whether AF was converted to sinus rhythm within 30 minutes after administration. ECG monitoring was performed during the injection of ibutilide. Atrial waves recorded by coronary sinus electrodes were measured for calculating average wavelength of AF waves in six seconds. The QT interval was measured immediately after conversion and 2 hours after injection of ibutilide. RESULTS: Forty patients whose AF was not converted to sinus rhythm after radiofrequency ablation were given an intravenous injection of ibutilide. Of the 40 patients, 29 cases were converted to sinus rhythm, with a conversion rate of 72.5%. The average conversion time was (13.2 ± 5.5) minutes. Compared with the conversion group, patients in the non-conversion group had a longer history of AF (9.4 ± 5.3) years vs. (4.3 ± 2.8) years, P < 0.05), and a markedly enlarged left atrium (47.3 ± 2.9) mm vs. (42.1 ± 4.5) mm, P < 0.05). There were no significant differences in gender, age, body mass index and left ventricular function between the two groups. Ibutilide significantly prolonged the average wavelength of the AF wave (171.8 ± 29.5) ms vs. (242.0 ± 40.0) ms, P < 0.001). Two hours after ibutilide treatment, the QT interval was significantly shortened (421.0 ± 24.7) ms vs. (441.0 ± 37.4) ms, P < 0.05). No cases of serious arrhythmias or other adverse reactions were found. CONCLUSIONS: A single dose of ibutilide for conversion of persistent or permanent AF after radiofrequency ablation is safe and effective.