Satoshi Higa

Focal Atrial Tachycardia

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.

Focal atrial tachycardia: new insight from noncontact mapping and catheter ablation.

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.

Consistency of complex fractionated atrial electrograms during atrial fibrillation

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 > or =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.

Efficacy of Additional Ablation of Complex Fractionated Atrial Electrograms for Catheter Ablation of Nonparoxysmal Atrial Fibrillation

Background: The efficacy of ablation of complex fractionated atrial electrograms (CFEs) in the single ablation procedure for nonparoxysmal atrial fibrillation (AF) patients is not well demonstrated. The aim of this study was to compare the ablation strategies of pulmonary vein isolation (PVI) plus linear ablation with and without additional ablation of CFEs in these patients.

Electrophysiological Characteristics and Catheter Ablation in Patients With Paroxysmal Right Atrial Fibrillation

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.

Spatiotemporal Organization of the Left Atrial Substrate After Circumferential Pulmonary Vein Isolation of Atrial Fibrillation

Background—There is a paucity of data regarding the mechanism of maintaining atrial fibrillation (AF) after pulmonary vein isolation (PVI) in patients with AF. The aim of this study was to examine the impact of circumferential PVI on the left atrial (LA) substrate characteristics. Methods and Results—Seventy-two AF patients (age, 53±11 years) underwent mapping and catheter ablation using an NavX system. The biatrial characteristics such as the complex fractionated atrial electrograms (CFEs; based on fractionated intervals) and frequency analysis (based on dominant frequencies) were mapped before and after PVI. PVI with electric isolation was performed in all patients. In the 45 patients who did not respond to PVI, the continuous CFEs (>8 seconds, 18±18% and 12±17% of the LA sites, before and after PVI, respectively, P=0.02), degree of LA fractionation (mean fractionated interval: 75.6±14.3 msec versus 87.3±16.7 msec, P=0.001), and mean LA dominant frequencies (6.92±0.88 Hz versus 6.58±0.91 Hz, P=0.001) decreased after PVI. Complete PVI altered the distribution of the CFEs toward the LA anteroseptum, mitral annulus, and LA appendage regions. A persistent presence of continuous CFEs in the vicinity of the dominant frequencies sites (observed in 53% patients) correlated with a higher procedural AF termination rate for the CFE ablation (63% versus 23%, P<0.05). Conclusions—Complete PVI eliminated some CFEs in the LA and altered the distribution of the CFEs. The persistent presence of CFEs before and after PVI in the vicinity of the high frequency sites is important for AF maintenance after PVI.

Predicting factors for atrial fibrillation acute termination during catheter ablation procedures: Implications for catheter ablation strategy and long-term outcome

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.

The Impact of Left Atrial Size on Long‐Term Outcome of Catheter Ablation of Chronic Atrial Fibrillation

Background: The left atrial (LA) size is an important predictor of atrial fibrillation (AF) procedural termination and the long‐term outcome. We sought to evaluate the long‐term outcome in regard to the LA size and procedural termination.

Cardioprotective effects of troglitazone in streptozotocin-induced diabetic rats.

Troglitazone, a new oral antidiabetic agent, shows hypoglycemic effects in insulin-resistant animal models and humans. This study was conducted to evaluate the effects of troglitazone on the heart of diabetic animals. Streptozotocin (STZ)-induced diabetic rats and age-matched controls were treated with troglitazone as a 0.2% food admixture for 6 weeks. Basal and postischemic cardiac functions at 14 weeks of age were then examined in isolated working heart. Troglitazone treatment did not attenuate the insulinopenia and hyperglycemia of diabetic rats, but it partially improved the hypertriglyceridemia. Troglitazone treatment partially restored the basal heart rate and cardiac work of diabetic rats to nearly control values. Troglitazone also improved the postischemic functional deficits of diabetic rats: heart rate (untreated 61% of baseline at 30-minute reperfusion v treated 92%, P < .001), left ventricular (LV) developed pressure (54% v 94%, P < .001), peak positive ([LV + dP/dt] 54% v 93%, P < .001) and negative ([LV -dP/dt] 53% v 94%, P < .001) first derivative of LV, and cardiac work (44% v 98%, P < .001). Diabetic animals showed ultrastructural damage including disarray of sarcomere, disorganization of mitochondrial matrix, cytoplasmic vacuolization, and invagination of nuclear membrane; these were partially normalized by troglitazone treatment. Our results suggest that troglitazone treatment has a cardiprotective effect on the basal and postischemic cardiac function of STZ-induced diabetic rats.

Heterogeneous expression of potassium currents and pacemaker currents potentially regulates arrhythmogenesis of pulmonary vein cardiomyocytes.

Introduction: The relationship between the determining factors and beating rates of pulmonary vein (PV) pacemaker cardiomyocytes has not been fully elucidated. The purposes of this study were to compare the electrophysiological characteristics between PV fast and slow pacemaker cardiomyocytes.