Philippe Ricard

Multicenter low energy transvenous atrial defibrillation (XAD) trial results in different subsets of atrial fibrillation

OBJECTIVES This prospective, multicenter trial was aimed at defining efficacy and safety of low energy shocks during atrial fibrillation in a diverse cohort of patients. BACKGROUND Experimental studies in sheep and preliminary data in humans have suggested that low energy internal shocks delivered between right atrial and coronary sinus electrode catheters may terminate atrial fibrillation. METHODS Biphasic 3/3-ms R wave synchronous shocks were delivered between two electrode catheters in the right atrium and coronary sinus. The defibrillation protocol started with a test shock of 20 V, and shocks increased in 40-V steps until restoration of sinus rhythm or a maximum of 400 V. Shock delivery was withheld after short RR intervals. In 141 patients with atrial fibrillation, the protocol was carried out under sedation in case the shock was associated with discomfort. The atrial arrhythmia was paroxysmal (< or = 7 days) in 50 patients, chronic (> 30 days) in 53, intermediate (> 7 days, < or = 30 days) in 18 and induced in 20. Underlying heart disease was present in 88 patients (62%). RESULTS Paroxysmal atrial fibrillation was successfully terminated in 46 (92%) of 50 patients, chronic atrial fibrillation in 37 (70%) of 53, intermediate in 16 (89%) of 18 and induced in 16 (80%) of 20. Mean conversion threshold was 1.8 J (213 V) in the induced group, 2.0 J (229 V) in the paroxysmal group, 2.8 J (272 V) in the intermediate group and 3.6 J (311 V) in the chronic group. The conversion voltage was significantly (p < 0.001) higher in the chronic group than in the other groups of atrial fibrillation and increased significantly with the duration of atrial fibrillation and with left atrial size (p < 0.05). Of 1,779 R wave synchronized shocks delivered with a mean (+/-SD) preceding RR interval of 676 +/- 149 ms, no ventricular arrhythmia was induced. The latter may occur after unsynchronized shocks. CONCLUSIONS Low energy transvenous shocks in patients with atrial fibrillation are effective and safe, provided that shocks are properly synchronized to R waves with preceding RR intervals that meet appropriate cycle length criteria. This study provides data that may be useful in the development of an implanted atrial defibrillator.

Low-Energy Cardioversion of Spontaneous Atrial Fibrillation Immediate and Long-term Results

BACKGROUND Recent studies have suggested that induced atrial fibrillation (AF) could be successfully terminated by using a two-catheter electrode system and low energy (< 400 V). This study evaluated the efficacy and safety of low-energy cardioversion in spontaneous chronic and paroxysmal AF. METHODS AND RESULTS Forty-two consecutive patients with spontaneous AF underwent low-energy electrical cardioversion. AF was chronic (> or = 1 month) with a mean duration of 9 +/- 19 months in 28 patients (group I) or paroxysmal with a history of recurrent attacks and a mean duration of the present episode of 7 +/- 16 days in 14 patients (group II). An underlying heart disease was present in 28 patients. A 3/3-ms biphasic shock was delivered between catheters positioned in the right atrium and the coronary sinus in 32 patients. In 10 patients, the left pulmonary artery branch was used. The catheters were connected to a custom external defibrillator. The shocks were synchronized to the R wave. Following a test shock of 60 V, the energy was increased in 40-V steps until a maximum of 400 V or restoration of sinus rhythm. Sinus rhythm was restored in 22 of the 28 patients (78%) of group I by using a mean leading-edge voltage of 297 +/- 57 V (mean energy 3.3 +/- 1.3 J) and in 11 of 14 patients (78%) of group II by using a mean leading-edge voltage of 223 +/- 41 V (mean energy, 1.8 +/- 0.7 J). The energy required for terminating chronic AF was significantly (P < .001) higher than that required for terminating paroxysmal AF. Among the other variables studied, the duration of AF significantly affected the successful voltage. Ventricular proarrhythmia occurred in 1 patient with atrial flutter due to an unsynchronized shock. Of the 22 patients of group I in whom sinus rhythm was restored, 14 (63%) remained in sinus rhythm with a mean follow-up of 9 +/- 3 months. Pain level showed a good correlation with increasing voltage. However, a marked inter-individual variation was noted. CONCLUSIONS Atrial defibrillation using low energy between two intracardiac catheters with an electrical field between the right and left atria and the protocol used is feasible in patients with persistent spontaneous AF. The technique is safe provided synchronization to the R wave is achieved. A low recurrence rate of AF was seen in patients in whom sinus rhythm was restored.

Paroxysmal A trial Fibrillation

Classification of Atrial Fibrillation. Introduction: Clinical aspects of paroxysmal atrial fibrillation are heterogeneous. The attacks of atrial fibrillation may differ in their duration frequency and presence and severity of symptoms. Therefore, a proposal for a clinical classification of paroxysmal atrial fibrillation may be helpful. We tested a new classification system in a cohort of 51 consecutive hospitalized patients with paroxysmal atrial fibrillation.

Robotic magnetic navigation for ablation of human arrhythmias: Initial experience

BACKGROUND Magnetic navigation system (MNS) (Niobe, Stereotaxis, Saint-Louis, Missouri, USA) allows remote control of a radiofrequency ablation catheter using a steerable magnetic field and a catheter advancement system. AIMS We report our initial experience of ablation of human arrhythmias using the MNS. METHODS Eighty-four patients (mean age 54+/-17years; 39 women) had an electrophysiologic study followed by ablation with the MNS using non-irrigated 4, 8 and 3.5mm-tip catheters with three distal magnets. All patients were symptomatic, with commonly-accepted indications for ablation: atrioventricular nodal re-entrant tachycardia (AVNRT; n=37); typical atrial flutter (n=15); accessory pathway (n=12); atypical atrial flutter (n=7); ventricular tachycardia (n=7); atrial tachycardia (n=3); paroxysmal atrial fibrillation (n=3). Electroanatomical mapping was used for atrial flutter, atrial fibrillation, atrial tachycardia and ventricular tachycardia procedures (29 patients, 34%). RESULTS Ablation was performed successfully in 69 (82%) patients. In 15 patients (18%), MNS technique was unsuccessful: seven typical atrial flutters, four accessory pathways, two left atrial flutters after atrial fibrillation ablation, one ventricular tachycardia and one AVNRT; in all these cases except one typical atrial flutter and two left atrial flutters, success was obtained by switching to the manual technique by means of an irrigated catheter. Total fluoroscopy time was 14+/-11minutes; operator exposure fluoroscopy time was 1.5+/-0.6minutes; procedure time was 169+/-72minutes. CONCLUSION MNS ablation is a feasible treatment for various human arrhythmias, with a high success rate. Mapping with a magnetic catheter is safe. However, magnetic ablation of typical atrial flutter remains challenging, probably because of insufficient pressure for cavotricuspid isthmus ablation.

Methods to determine bidirectional block of the cavotricuspid isthmus in radiofrequency ablation of typical atrial flutter.

At the time of initial complete bidirectional isthmus conduction block (CBIB) identification as the best predictor of long-term success for ablation of typical atrial flutter, the assessment required detailed mapping of activation at both sides of the ablation line during proximal coronary sinus (PCS) and antero-inferior right atrium (AIRA) pacing.1 Complete block after radiofrequency applications was clearly associated with a change of activation pattern at the AIRA compared to baseline and this implied the use of three catheters (one for mapping each side of the ablation zone and one for ablation). Like any new concepts it brought as many questions as answers. Technically speaking mapping of the AIRA had to be done as anteriorly as possible as the circuit in its typical form is peritricuspidian. Standard multipolar catheters bend in a single plane and are thus hard to manipulate in this area as they have a tendency to stay posterior in the lateral right atrium. In addition, even if they stay close to the tricuspid annulus, the tip of the catheter rarely reaches the area close from the ablation line. As a consequence, this leaves a large unmapped area which is why we favored the use of multipolar preshaped catheters (commonly referred to as “Halo catheter.” Most of these incorporate a high number of electrodes (typically 20) but all dipoles are not equally useful and indeed the two most distal are sufficient to assess conduction in the immediate vicinity of the ablation line. In practice, we use a decapolar Halo catheter for reasons explained below. Several methods have later been proposed and the purpose of this article is to review the technique used for assessment of the conduction block during catheter ablation of atrial flutter in our laboratory. Surface ECG changes have been proposed with CBIB as appearance of a purely descending lateral RA wavefront during PCS pacing accompanied by a positive second part of the paced P wave, but this lacks sensitivity and specificity and we do not use it. Unipolar mapping using the ablation electrode has proven effective when a change from a RS pattern before block to a single monophasic R after identifies the end of the activation wave front. We also do not use it as it seems a bit more difficult to interpret and has not been stud-

Slow Pathway Radiofrequency Ablation in Patients with AVNRT: Junctional Rhythm is Less Frequent during Magnetic Navigation Ablation Than with the Conventional Technique

Introduction: The occurrence of accelerated junctional rhythm (JR) during radiofrequency ablation of the slow pathway in patients with atrioventricular nodal reentrant tachycardia (AVNRT) is frequent. The aim of the present study was to compare the occurrence of JR during magnetic remote catheter ablation to the conventional manual ablation.

Atrial fibrillation disorganization is reduced by catheter ablation: A standard ECG study

Selection of candidates to catheter ablation (CA) of long-lasting persistent atrial fibrillation (AF) is challenging, since success is not guaranteed. In this study, we put forward an automated method for noninvasively evaluating the reduction of the complexity of the AF organization following CA. Complexity is meant as the amount of disorganization observed on the ECG, supposed to be directly correlated to the number and interactions of atrial wavefronts. By means of PCA, the complexity of the AF organization is evaluated quantitatively from a 12-lead ECG recording. Preliminary results show that CA is able to reduce the complexity of AF organization in the atrial wavefront pattern propagation, despite the persistence of AF in most cases. This can be viewed as a first clinical validation of this parameter. Whether AF complexity and its reduction by CA are predictive of long-term outcome is thus still to be determined.

Hepatico-tricuspid isthmus ablation for typical-like atrial flutter by femoral approach in absence of the inferior vena cava: use of magnetic navigation and three-dimensional mapping with image integration.

The previously unknown congenital absence of inferior vena cava, an otherwise benign condition, may create difficulties for catheter ablation of arrhythmias. We describe a case of a typical‐like atrial flutter, in which magnetic navigation was important for conserving the femoral approach. Electroanatomic mapping with image integration helped define the critical isthmus between the ostia of the suprahepatic veins and the tricuspid valve. (PACE 2012; 35:e312–e315)

Thromboaspiration of left atrial clot during ablation of atrial fibrillation.

We describe a case during which a left atrial thrombus was visualized within the left atrium attached to a circular catheter during an atrial fibrillation ablation procedure. This was managed by successful thromboaspiration using a steerable sheath, preventing a potential serious complication.

Characteristics of recurrent clockwise atrial flutter after previous radiofrequency catheter ablation for counterclockwise isthmus-dependent atrial flutter.

AIMS Isthmus-dependent (ID) clockwise (CW) atrial flutters (AFl) are rare in comparison with counterclockwise (CCW) AFl. Little is known about clinical and electrophysiological characteristics of CW AFl occurring after previous radiofrequency (RF) catheter ablation of CCW AFl. We sought to compare CW AFl de novo vs. CW AFl occurring after previous CCW AFl RF ablation. METHODS AND RESULTS A total of 246 procedures of RF catheter ablation for AFl from January 2009 to January 2011 were reviewed. Clinical and electrophysiological data were analysed. Patients were excluded if they were in sinus rhythm at the beginning of the procedure, if they had concomitant/previous atrial fibrillation ablation, or if AFl was not ID. Twenty-seven patients presented CW AFl (10.9% of all ID AFl), including 10 CW AFl occurring after a previous RF catheter ablation for CCW AFl. Mean time for recurrence after the previous procedure of CCW AFl RF ablation was 3.5 years. They were younger (61.6 ± 11 years) than patients with CW AFl de novo (74.0 ± 7.2 years; P = 0.005). Bidirectional isthmus block was obtained in all patients. There was a significant difference in terms of double potential separation after ablation (155 ± 31 ms for CW AFl de novo vs. 111 ± 7 ms for recurrent CW AFl; P = 0.028). No differences were observed concerning CHADS score, AFl cycle length, and electrocardiogram typical pattern for CW AFl between the two groups. CONCLUSION Patients with CW AFl occurrence after CCW AFl RF catheter ablation are younger than patients with CW AFl de novo. They also have a smaller interspike interval after block completion.