Unipolar Signal Modification as a Guide for Lesion Creation During Radiofrequency Application in the Left Atrium

Abstract

P ulmonary vein isolation (PVI) is the cornerstone for catheter ablation procedures in patients with paroxysmal atrial fibrillation (AF).1 However, there is current concern about the durability of PVI because the PV reconnection rate has been recognized as substantial and clearly associated with the recurrence of paroxysmal AF episodes. 2 Editorial see p 1050 Clinical Perspective on p 1102PV reconnection may be related to the inability to create transmural and irreversible lesions around PV ostia. 3,4 In this regard, it has been demonstrated in a porcine model that complete elimination of the negative component of the unipolar atrial electrogram (EGM), while applying radiofrequency (RF) energy, was always associated with transmural lesions, whereas the persistence of such a negative component was constantly observed in case of nontransmural lesions. 5 In clinical practice, unipolar signal modification could be a suitable electrophysiological criterion that indicates when to halt each RF energy application while performing point-bypoint PVI (because a possible transmural lesion has been created) and when to continue its application (because the lesion deployed is presumed as not transmural).Therefore, we performed a prospective study to determine whether the unipolar signal modification may be useful or not as an end point for point-by-point RF application and find out whether it could improve the clinical results of paroxysmal AF ablations in humans by allowing more durable PVI achievement. We compared the results of the present study with those of a historical group of patients with paroxysmal AF who have undergone PVI following the standard ablative approach of our institution.© 2013 American Heart Association, Inc. Circ Arrhythm Electrophysiol Original ArticleBackground-In patients treated for paroxysmal atrial fibrillation, the pulmonary vein (PV) reconnection rate is substantial and may be related to the lack of transmurality achievement while performing PV isolation (PVI). It has been experimentally demonstrated that positive unipolar atrial electrogram completion, when applying radiofrequency energy, was associated with transmural lesions. In this regard, we seek to determine whether the unipolar signal modification may be an appropriate end point for point-by-point radiofrequency application and find out whether it could improve the paroxysmal atrial fibrillation ablation results in humans. Methods and Results-Fifty consecutive patients (61±8 years old, 41 men) with paroxysmal atrial fibrillation underwent PVI using Carto and Lasso. Each radiofrequency application lasted until development of a completely positive unipolar electrogram. Fifty patients (63±9 years old, 40 men), who previously underwent PVI following the standard approach of our institution, corresponded to the control group. All PVs were isolated in all patients of both groups. However, the procedural and ablation times were significantly lower in the unipolar group compared with those of the control group, whereas the PV reconnection rate...

Catheter Ablation of Lone Atrial Fibrillation

“…Controversial data about influence of older age on the periprocedural complications were published. For example, one study showed no significant difference between major complication rates of the AF ablation in three different age groups of patients, namely <65 years, [65][66][67][68][69][70][71][72][73][74] years and ≥75 years (1.6% vs. 1.7% vs. 2.9%, p=ns) [126]. On the contrary, the other two studies demonstrated strong association between the occurrence of complication and older age of >70 and ≥75 years [127,128].…”

“…Subsequent ablation of these fibers can significantly increase the efficiency of the first intervention [62][63][64]. It seems that the loss of capture on the ablative line, ablation guided by atrial unipolar signal modification and development of contact-force technology could provide better transmurality, continuity and durability of ablative lesion [27,[65][66][67][68].…”

Impedance-guided Radiofrequency Ablation: Using Impedance to Improve Ablation Outcomes

“…6 Similarly, the creation of a completely positive unipolar signal has also been associated with transmural lesion formation, and achievement of this endpoint has been associated with improved outcomes after AF ablation. 7 However, the assessment of real-time EGM diminution is difficult to quantify in real time, and can also be misleading, as changes in catheter position and cathetertissue contact can alter EGM morphology and amplitude. Indeed EGM diminution can reflect either actual tissue destruction or, simply, the absence of adequate contact between the ablation catheter and the tissue.…”

Initial Experience with the BioSig PURE EP™ Signal Recording System: An Animal Laboratory Experience

“…The ultimate solution is improved front-end filtering so that acquired and displayed waveforms are visible and clean during the application of RF energy. 17,18,[21][22][23] Unfortunately, in conventional recording systems, unipolar signals referenced to WCT tend to be noisy. The low cut-off frequency for the highpass filter requires an expanded dynamic range to fully capture the recorded signals with baseline drift.…”