Lam Dang

Evaluation of ablation patterns using a biophysical model of atrial fibrillation

Atrial fibrillation (AF) is the most common form of cardiac arrhythmia. Surgical/Radiofrequency (RF) ablation is a therapeutic procedure that consists of creating lines of conduction block to interrupt AF. The present study evaluated 13 different ablation patterns by means of a biophysical model of the human atria. In this model, ablation lines were abruptly applied transmurally during simulated sustained AF, and success rate, time to AF termination and average beat-to-beat interval were documented. The gold standard Cox’s Maze III procedure was taken as reference. The effectiveness of twelve less invasive patterns was compared to it. In some of these incomplete lines (entailing a gap) were simulated. Finally, the computer simulations were compared to clinical data. The results show that the model reproduces observations made in vivo: (1) the Maze III is the most efficient ablation procedure; (2) less invasive patterns should include lines in both right and left atrium; (3) incomplete ablation lines between the pulmonary veins and the mitral valve annulus lead to uncommon flutter; (4) computer simulations of incomplete lines are consistent with clinical results of non-transumural RF ablation. Biophysical modeling may therefore be considered as a useful tool for understanding the mechanisms underlying AF therapies.

Duty-cycled unipolar/bipolar versus conventional radiofrequency ablation in paroxysmal and persistent atrial fibrillation

BACKGROUND Duty-cycled (DC) radiofrequency ablation (RFA) for atrial fibrillation (AF) has been introduced, however, data on large patient series and comparison to conventional RFA are scarce. METHODS Between 2006 and 2008 DC RFA was performed in 209 consecutive patients (143 (68%) paroxysmal and 66 (32%) persistent AF). As controls served 211 patients, 155 (73%) with paroxysmal and 56 (27%) with persistent AF (p=0.3). In DC RFA, the pulmonary veins (PV) were isolated followed by ablation at the septum and left atrium, if AF persisted. Conventional PV isolation was followed by anatomical lines at the roof and mitral isthmus. RESULTS Freedom of paroxysmal AF was demonstrated after 1.08 DC RFA procedures per patient in 82% and after 1.19 conventional procedures in 87% after 8.5 ± 6.5 months (ns). In persistent AF, success rates were 79% after 1.35 DC RFA procedures and 80% after 1.34 conventional procedures after 11.5 ± 8.5 months (ns). The subgroup analysis of 119 patients with follow-up ≥ 12 months (17.5 [14.1-23.6] months) showed similar results. Left atrial flutter occurred in 3% and 8% after paroxysmal AF ablation (p < 0.05) and in 12% and 23% after persistent AF ablation (p=0.1). Multivariate predictors for success in both groups were age, left atrial size, presence of persistent vs. paroxysmal AF and previous pacemaker implantation, but not the ablation technique used. Non-fatal complications were seen in 2.8% with no differences between the groups. CONCLUSION Outcome in DC RFA is similar to conventional RFA with a final success rate exceeding 80% in both paroxysmal and persistent AF in the absence of fatal complications.

Impact of Varying Ablation Patterns in a Simulation Model of Persistent Atrial Fibrillation

Background: Several strategies of endovascular ablation with varying success rates and proarrhythmic effects have been proposed to treat persistent atrial fibrillation (AF). Evaluation of ablation patterns by computer simulation provides a tool for examination of its effectiveness and side effects.

Linear Ablation with Duty-Cycled Radiofrequency Energy at the Cavotricuspid Isthmus

Background: Multielectrode catheters using duty‐cycled radiofrequency (RF) have been developed to treat atrial fibrillation (AF). Many of these patients also have atrial flutter. Therefore, a linear multielectrode has been developed using the same RF energy.

Initial Results of Linear Duty‐Cycled Radiofrequency for Atypical Flutter and Atrial Tachycardia

Background: Duty‐cycled radiofrequency (DCRF) is increasingly used for ablation of atrial fibrillation (AF). Many patients also have atrial flutter (AFL). Recently, a linear multielectrode has been shown to create linear block at the cavotricuspid isthmus and in the left atrium (LA).

Characterizing Anti-Tachy Pacing Efficiency in a Numerical Model of Human Atrial Arrhythmias

Keywords: LTS1 Reference LTS-CONF-2003-007View record in Web of Science Record created on 2006-06-14, modified on 2016-08-08

Epicardial Wolff–Parkinson–White ablation

A 45-year-old female patient without structural heart disease was referred for redo Wolff–Parkinson–White (WPW) ablation after an unsuccessful endocardial procedure. The refractory period of the accessory pathway had been measured at 230 ms and antiarrhythmic treatment with flecainide was unsuccessful. 1. The surface electrogram shows the largest negative δ-wave in lead III. 2. During endocardial mapping …

Quasi-periodic atrial activity components in the ECG used to discriminate between paroxysmal and chronic atrial fibrillation

Spatiotemporal organization in atrial fibrillation has recently been observed in invasive studies with a left-to-right frequency gradient. We propose the use of a recently developed technique named phase-rectified signal averaging to estimate the mean activation rates in leads V1 and V5 to observe the same left-to-right gradient in a noninvasive manner. Based on these values, a classification procedure between paroxysmal (n=43) and chronic (n=20) atrial fibrillation patient is suggested. The processing steps were: baseline correction and ventricular activity cancellation, followed by the phase-rectified signal averaging technique. The three features used were the dominant frequency values of leads V1 and V5 and the absolute value of the difference between these frequencies. These yielded to 84.1% of correct classifications (p < 8.5 times 10-7).