Olivier Xhaet

Remote magnetic navigation with irrigated tip catheter for ablation of paroxysmal atrial fibrillation

Background—The remote magnetic navigation system (MNS) has been used with a nonirrigated magnetic catheter for atrial fibrillation (AF) ablation. The objective of this study was to evaluate the feasibility and efficiency of the newly available irrigated tip magnetic catheter for index pulmonary vein isolation (PVI) in patients with paroxysmal AF (PAF). Methods and Results—Between January 2008 and June 2009, 30 consecutive patients with drug-resistant PAF underwent circular mapping catheter-guided PVI with MNS (MNS group). The outcomes were compared retrospectively with those of a conventional hand-controlled ablation technique during the same period in 44 consecutive patients (manual group). All 4 pulmonary veins were successfully isolated in both groups except in 4 patients in the MNS group. Radiofrequency and procedure duration were higher in the MNS group (60±27 versus 43±16 minutes; P=0.0019) than in the manual group (246±50 versus 153±51 minutes; P<0.0001). In the patients who underwent only PVI, total fluoroscopic time also was longer in the MNS group than in the manual group (58±24 versus 40±14 minutes; P=0.0002). At 12-month follow-up after a single procedure, 69.0% of the patients in MNS group and 61.8% of patients in manual group were free of atrial tachyarrhythmia without antiarrhythmic drugs. There was no significant difference in the atrial tachyarrhythmia-free survival between the 2 groups (P=0.961). Cardiac tamponade occurred in 1 patient in the manual group. Conclusions—In patients with PAF, MNS-guided PVI with the newly available irrigated tip magnetic catheter backed up with manual ablation whenever required is feasible. However, it requires longer ablation, fluoroscopy, and procedural times than the conventional approach in the early experience stage.

Validation of novel 3-dimensional electrocardiographic mapping of atrial tachycardias by invasive mapping and ablation: A multicenter study

OBJECTIVES This study prospectively evaluated the role of a novel 3-dimensional, noninvasive, beat-by-beat mapping system, Electrocardiographic Mapping (ECM), in facilitating the diagnosis of atrial tachycardias (AT). BACKGROUND Conventional 12-lead electrocardiogram, a widely used noninvasive tool in clinical arrhythmia practice, has diagnostic limitations. METHODS Various AT (de novo and post-atrial fibrillation ablation) were mapped using ECM followed by standard-of-care electrophysiological mapping and ablation in 52 patients. The ECM consisted of recording body surface electrograms from a 252-electrode-vest placed on the torso combined with computed tomography-scan-based biatrial anatomy (CardioInsight Inc., Cleveland, Ohio). We evaluated the feasibility of this system in defining the mechanism of AT-macro-re-entrant (perimitral, cavotricuspid isthmus-dependent, and roof-dependent circuits) versus centrifugal (focal-source) activation-and the location of arrhythmia in centrifugal AT. The accuracy of the noninvasive diagnosis and detection of ablation targets was evaluated vis-à-vis subsequent invasive mapping and successful ablation. RESULTS Comparison between ECM and electrophysiological diagnosis could be accomplished in 48 patients (48 AT) but was not possible in 4 patients where the AT mechanism changed to another AT (n = 1), atrial fibrillation (n = 1), or sinus rhythm (n = 2) during the electrophysiological procedure. ECM correctly diagnosed AT mechanisms in 44 of 48 (92%) AT: macro-re-entry in 23 of 27; and focal-onset with centrifugal activation in 21 of 21. The region of interest for focal AT perfectly matched in 21 of 21 (100%) AT. The 2:1 ventricular conduction and low-amplitude P waves challenged the diagnosis of 4 of 27 macro-re-entrant (perimitral) AT that can be overcome by injecting atrioventricular node blockers and signal averaging, respectively. CONCLUSIONS This prospective multicenter series shows a high success rate of ECM in accurately diagnosing the mechanism of AT and the location of focal arrhythmia. Intraprocedural use of the system and its application to atrial fibrillation mapping is under way.

Early Temporal and Spatial Regularization of Persistent Atrial Fibrillation Predicts Termination and Arrhythmia-Free Outcome

BACKGROUND Termination of persistent atrial fibrillation (AF) is a valuable ablation endpoint but is difficult to anticipate. We evaluated whether temporal and spatial indices of AF regularization predict intraprocedural AF termination and outcome. OBJECTIVE The purpose of this study was to test whether temporospatial organization of AF after pulmonary vein isolation (PVI) predicts whether subsequent stepwise ablation will terminate persistent AF or predict outcome. METHODS In 75 patients with persistent AF, we measured AF cycle length (AFCL), temporal regularity index (TRI, a spectral measure of timing regularity), and spatial regularity index (SRI, cycle-to-cycle variations in spatial vector) between right atrial appendage and proximal and distal coronary sinus before and during stepwise ablation to the endpoint of AF termination. RESULTS AF termination was achieved in 59 patients (79%) by ablation. AF terminated during PVI in 11 patients, who were excluded from analysis. In the remaining 48 patients, TRI and SRI increased during stepwise ablation, as compared with 16 patients without termination (P<.05). AFCL was prolonged in both groups. From receiver operating characteristics analysis of the first 22 patients (training set), a post-PVI TRI increase predicted AF termination in the latter 42 patients (test set) with a positive predictive value of 96%, negative predictive value of 53%, sensitivity of 71%, and specificity of 91%. Results were similar for SRI. After 36 months, higher arrhythmia-free outcome was observed in patients in whom PVI caused temporospatial regularization in AF. CONCLUSIONS Temporal and spatial regularization of persistent AF after PVI identifies patients in whom stepwise ablation subsequently terminates AF and prevents recurrence.

Atrial Tachycardias Arising from Ablation of Atrial Fibrillation: A Proarrhythmic Bump or an Antiarrhythmic Turn?

The occurrence of atrial tachycardias (AT) is a direct function of the volume of atrial tissue ablated in the patients with atrial fibrillation (AF). Thus, the incidence of AT is highest in persistent AF patients undergoing stepwise ablation using the strategic combination of pulmonary vein isolation, electrogram based ablation and left atrial linear ablation. Using deductive mapping strategy, AT can be divided into three clinical categories viz. the macroreentry, the focal and the newly described localized reentry all of which are amenable to catheter ablation with success rate of 95%. Perimitral, roof dependent and cavotricuspid isthmus dependent AT involve large reentrant circuits which can be successfully ablated at the left mitral isthmus, left atrial roof and tricuspid isthmus respectively. Complete bidirectional block across the sites of linear ablation is a necessary endpoint. Focal and localized reentrant AT commonly originate from but are not limited to the septum, posteroinferior left atrium, venous ostia, base of the left atrial appendage and left mitral isthmus and they respond quickly to focal ablation. AT not only represents ablation-induced proarrhythmia but also forms a bridge between AF and sinus rhythm in longstanding AF patients treated successfully with catheter ablation.

Initial results of efficacy of left linear ablation using a novel simultaneous multielectrode ablation catheter.

LA Linear Ablation With Multielectrode Catheter. Introduction: Creating complete linear block with point‐by‐point ablation is challenging in the left atrium (LA). The purpose of this study was to evaluate the efficacy of LA linear ablation using a hexapolar linear multielectrode mapping/ablation catheter.

Intravenous Adenosine to Predict Conduction Recurrence in Cavotricuspid Isthmus Early After Ablation of Typical Atrial Flutter: Myth or Reality?

Adenosine and Ablation of Typical Atrial Flutter. Introduction: Early recovery of conduction (ER) after cavotricuspid isthmus (CTI) ablation for typical atrial flutter (AFl) occurs in approximately 10% of the patients. If not recognized, ER might lead to AFl recurrences. In this study, we hypothesized that intravenous adenosine (iADO) can be used to predict ER in the CTI immediately after RF ablation and distinguish functional block from the complete destruction of the CTI myocardium.

Impact of patent foramen ovale on left atrial linear lesions in the context of atrial fibrillation ablation

Impact of PFO on LA Linear Ablation. Introduction: We investigated the impact of the mode of left atrial (LA) access via patent foramen ovale (PFO) versus transseptal (TS) puncture on LA linear lesions during atrial fibrillation (AF) ablation.

Preprocedural Clinical Parameters Determining Perimitral Conduction Time During Mitral Isthmus Line Ablation

Background—Achievement of complete conduction block across left mitral isthmus (MI) is challenging. Anticipation of perimitral conduction time (PMCT) associated with MI block may expedite this procedure. We evaluated the relationship between the preprocedural variables and the quantum of PMCT in patients with bidirectionally blocked MI. Methods and Results—We reviewed clinical and echocardiographic parameters in 290 consecutive patients with confirmed bidirectional MI block during atrial fibrillation (AF) ablation. PMCT was defined as the temporal delay to the latest of the double potentials on the line of block while pacing posteroseptal to it in the left atrium (LA). LA size and type of AF significantly influenced PMCT in multivariate analysis. A cumulative score based on LA size (0≦45 mm; 1>45 mm) and type of AF (0: paroxysmal; 1=nonparoxysmal) ranged from 0 to 2. PMCT was directly correlated to the cumulative score (0: 169 ms; n=78; 95% confidential interval, 156 to 181); 1: 187 ms; n=103; 95% confidential interval, 178 to 196; 2: 209 ms; n=109; 95% confidential interval, 200 to 217). In 61 patients who underwent AF ablation twice, the difference between 2 PMCT values was <30 ms in 75% patients. Another consecutive 143 patients with and without MI block after at least 15 minutes of radiofrequency application were analyzed. Perimitral conduction delay <130 ms ruled out bidirectional MI block. Perimitral conduction delay >173 ms predicted bidirectional block with an accuracy of 86%. Conclusions—LA size and AF type significantly influence PMCT in patients undergoing successful MI ablation. These parameters can be used to predict the time value associated with MI block, preprocedurally.

Mitral Isthmus Block in a Case of Persistent Left Superior Vena Cava

Mitral Isthmus Block in Superior Vena Cava.  Persistent left superior vena cava (LSVC), an uncommon venous anomaly, could be an arrhythmogenic source of atrial fibrillation. Multiple electrical connections were reported between the LSVC and the left atrium, which may negatively impact the achievement of conduction block during linear ablation of left mitral isthmus. We describe a case with perimitral atrial flutter (AFL) in a patient with isolated LSVC. AFL was successfully treated and complete perimitral conduction block was achieved following a lengthy epicardial radiofrequency application. (J Cardiovasc Electrophysiol, Vol. 22, pp. 343‐345, March 2011)

Integrity of the Ganglionated Plexi is Essential to Parasympathetic Innervation of the Atrioventricular Node by the Right Vagus Nervez

Radiofrequency isolation of pulmonary vein can be accompanied by transient sinus bradycardia or atrioventricular nodal (AVN) block, suggesting an influence on vagal cardiac innervation. However, the importance of the atrial fat pads in relation with the vagal innervation of AVN in humans remains largely unknown. The aim of this study was to evaluate the role of ganglionated plexi (GP) in the innervation of the AVN by the right vagus nerve.