A Comprehensive Overview of Ablation of Paroxysmal, Persistent, and Permanent Atrial Fibrillation: A Stepwise Approach
Pierre Jaïs
Seiichiro Matsuo
Kang-Teng Lim
Mélèze Hocini
Sébastien Knecht
Leonardo Arantès
Pierre Bordachar
Jacques Clémenty
Michel Haïssaguerre
Most patients with structurally normal hearts and short episodes (<24 hours) of paroxysmal atrial fibrillation (PAF) can be successfully treated using ablation techniques to isolate the pulmonary veins (PVs) from the left atrium (LA). However, extension of this simple strategy to patients with resistant paroxysmal, persistent, or permanent AF is much less effective (1). For these challenging patients, the recognition of the importance of non-PV sites in the initiation and maintenance of AF has led to the development of novel ablation strategies to target the atrial myocardium beyond the PV-LA junction. In addition to pulmonary vein isolation (PVI), extended ablation schemas have evolved to target areas of complex fractionated activity (CFAE) (2), short cycle-length activity (3), or sites of dominant frequency (4) to interrupt reentrant wavelets by creating continuous LA linear lesions between anatomical barriers (5,6) and to exclude the PV antrum incorporating the posterior LA (7).
To summarize, two different types of strategies have been proposed; consisting in using predetermined ablation schema, they usually include linear lesions at the LA roof and mitral isthmus (5,8) or, to tailor the ablation procedure to the patient, use an electrogram-based approach (3,9). These two approaches are fundamentally different and most authors recognize now that a one-size-fits-all ablation schema is unlikely to be successful.
In an effort to assess the benefit of each of the ablation strategies, they have been performed in a random order, the steps most-frequently associated with a conversion from AF to AT or to sinus rhythm are PVI, ablation at the inferior LA-coronary sinus (CS) and the left atrial appendage (LAA) mouth, followed by linear lesions at the LA roof and mitral isthmus (3). Accordingly, a sequential procedure has been used in our department and is reported here.
Electrophysiologic StudyWhen possible, amiodarone is maintained or initiated prior to the ablation procedure. This is associated with a prolongation of the AF cycle length and may facilitate the ablation by reducing the amount of lesions required to convert AF. This strategy has not been proved to be effective and remains speculative at the moment. Effective oral anticoagulation is required (target INR 2.0-3.0) for at least 1 month prior to the procedure and a transesophageal echocardiogram is performed within 5 days of the procedure to exclude atrial thrombi.
The procedure is performed during conscious sedation using midazolam and morphine. This strategy may be superior to general anesthesia as it may have the advantage of preventing esophageal injury by allowing the patient to complain about excessive pain. In addition, a stroke would be diagnosed immediately, allowing for a rapid thrombolysis if required. This is critical to maximize both safety and efficacy of the thrombolysis.
Surface electrocardiogram and bipolar endocardial electrograms are continuously monitored and stored on a computer-based digital amplifier/recorder system (Lab-System Pro, Bard Electrophysiology). Intracardiac electrograms are filtered from 30 to 500 Hz.
The following catheters are introduced via the right common femoral vein for electrophysiologic study:
A steerable quadripolar catheter (5-mm electrode spacing, Xtrem, ELA Medical) positioned within the CS with the proximal electrode at 4 to 5 o’clock along the mitral annulus in the 30° left anterior oblique projection
A 10-pole fixed-diameter circumferential mapping catheter (Lasso, Biosense-Webster) introduced following transseptal access and stabilized with the aid of a long sheath (Preface multipurpose, Biosense-Webster), which is continuously perfused with heparinized dextrose (250 cc; 2500 IU of heparin)
An irrigated-tip ablation catheter with a distal 3.5-mm tip and three 1-mm electrodes separated by 2 × 5 × 2-mm interelectrode spacings (ThermoCool, Biosense-Webster). Following transseptal puncture, a single bolus of 50 IU/kg of heparin is administered and repeated for procedures lasting longer than 4 hours, or if the activated clotting time (ACT) falls below 250 seconds.
Measurement of Atrial Fibrillation Cycle LengthImmediately following transseptal access, the mapping catheter is advanced to the LAA, the diagnostic catheter positioned in the right atrial appendage (RAA), and simultaneous recording of at least 30 cycles is performed. Using custom software (Bard EP), the mean AFCL and the range of AFCL for the selected window is calculated and the annotation is then verified manually online to ensure accuracy. Inter-electrogram intervals of less than100 ms or continuous electrical activity are manually corrected to count as a single interval. However, the electrograms within the LAA are usually discrete and of high amplitude (usually 0.5-2.0 mV), thereby facilitating unambiguous automatic annotation of the electrogram. Following PVI, the Lasso catheter is withdrawn from the LA and positioned within the RAA to allow simultaneous recording of LAA and RAA cycle lengths before and after each ablation step using the irrigated-tip catheter (in the LAA) and Lasso catheter (in the RAA), respectively (Fig. 16.1).
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