Pulmonary Vein Isolation : Comparison of Bipolar and Unipolar Electrograms At Successful and Unsuccessful Ostial Ablation Sites
Hiroshi TadaShigeto NaitohItaru ItohHiroshi FukazawaShigeru OoshimaKoich TaniguchiAkihiko NogamiFred Morady
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BACKGROUND -Radiofrequency catheter ablation of atrial fibrillation(AF) guided by complex fractionated atrial electrograms has been reported to eliminate AF in a large proportion of patients. However,only a small number of patients with chronic AF have been included in previous studies. METHODS AND RESULTS -In 100 patients(mean age,57± 11 years) with chronic AF,radiofrequency ablation was performed to target complex fractionated atrial electrograms at the pulmonary vein ostial and antral areas,various regions of the left atrium,and the coronary sinus until AF terminated or all identified complex fractionated atrial electrograms were eliminated. Ablation sites consisted of ≥ 1 pulmonary vein in 46% of patients; the left atrial septum,roof,or anterior wall in all; and the coronary sinus in 55% . During 14± 7 months of follow-up after a single ablation procedure,33% of patients were in sinus rhythm without antiarrhythmic drugs,38% had AF,17% had both AF and atrial flutter,9% had persistent atrial flutter,and 3% had paroxysmal AF on antiarrhythmic drugs. A second ablation procedure was performed in 44% of patients. Pulmonary vein tachycardia was found in all patients in both previously targeted and nontargeted pulmonary veins. There were multiple macroreentrant circuits in the majority of patients with atrial flutter. At 13± 7 months after the last ablation procedure,57% of patients were in sinus rhythm without antiarrhythmic drugs,32% had persistent AF,6% had paroxysmal AF,and 5% had atrial flutter. CONCLUSIONS -Modest short-term efficacy is achievable with radiofrequency ablation of chronic AF guided by complex fractionated atrial electrograms,but only after a second ablation procedure in 40% of patients. Rapid activity in the pulmonary veins and multiple macroreentrant circuits are common mechanisms of recurrent atrial arrhythmias.
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To analyze the unipolar electrogram from successful and unsuccessful ablation sites of focal atrial tachycardia (AT), and to evaluate its value in the identification of successful targets.Fifteen consecutive patients with focal AT were referred for radiofrequency catheter ablation (RFCA). Both unipolar (from the tip electrode of ablating catheter) and bipolar (from the distal pair of electrode of ablating catheter) electrograms were used to identify the ablation targets of focal AT.Successful ablation was echieved in 14 patients. Radiofrequency energy was delivered at a total of 27 sites. The bipolar electrograms associated with successful ablation sites showed earlier atrial deflection relative to P wave onset (36 ms +/- 15 ms vs 30 ms +/- 11 ms, P < 0.05) than the electrograms associated with failed ablation sites. At the 14 successful ablation sites, the unipolar electrograms displayed a completely negative atrial wave ("QS" morphology) beginning with intrinsic deflection. However, at the 13 unsuccessful ablation sites, a "rS" morphology of atrial wave was shown on the unipolar electrogram.The "QS" morphology of the atrial wave on unipolar electrograms appears to represent a reliable marker for identifying the successful ablation targets of focal AT, with a high sensitivity and specificity.
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Electrogram Analysis. Introduction: No prior studies have quantitatively analyzed the characteristics of bipolar or unipolar electrograms that may be helpful in identifying successful ostial ablation sites in patients with atrial fibrillation undergoing segmental pulmonary vein isolation. Methods and Results: The characteristics of bipolar and unipolar electrograms recorded at 185 successful and 120 unsuccessful ostial pulmonary venous ablation sites were analyzed in 21 patients with atrial fibrillation. A decapolar Lasso catheter was positioned near the ostia of the pulmonary veins, and a conventional ablation catheter was used to deliver radiofrequency energy at individual ostial sites where pulmonary vein potentials were recorded. With both bipolar and unipolar recordings, the only timing parameter that distinguished successful from unsuccessful ostial ablation sites was the timing of the electrogram recorded by the ablation catheter relative to the earliest pulmonary vein potential recorded by the Lasso catheter. With both bipolar and unipolar recordings, electrograms demonstrated a larger amplitude at successful than at unsuccessful ablation sites. Unipolar electrograms had a steeper intrinsic deflection at successful than at unsuccessful ostial ablation sites. The morphologies of the unipolar electrograms recorded by the ablation catheter and by the contiguous electrode of the Lasso catheter usually were identical. Conclusion: In patients undergoing segmental isolation of the pulmonary veins, unipolar recordings provide more information than bipolar recordings helpful in distinguishing successful from unsuccessful ostial ablation sites. Furthermore, unipolar recordings, but not bipolar recordings, allow accurate localization of the position of the ablation catheter relative to the electrodes of the Lasso catheter.
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Objectve To analyse the unipolar electrograms from successful and unsuccessful ablation sites of focal atrial tachycardia(AT),and evaluate the value of unipolar electrogram in identification of successful target. Methods Fifteen consecutive patients with focal AT were referred for radiofrequency catheter ablation(RFCA).Both unipolar (from the tip electrode of ablating catheter) and bipolar (from the distal pair of electrodes of ablating catheter)electrograms were recorded and used to identify the ablation target of focal AT. Results Successful ablation was obtained in 14 patients.Radiofrequency energy was delivered at a total of 27 atiral sites.The bipolar electrograms associated with successful ablation sites showed an earlier atrial deflection relative to P′ wave oneset [(36±15)]versus (30±11) ms, P 0.05)than the electrograms associatd with failed ablation sites.At the 14 successful abltaion sites,unipolar electrogram displayed a completely negative atrial wave (“QS” morphology) beginning with intrinsic deflection.However,at the 13 unsuccessful ablation sites,an “rS” morphology of atiral wave was shown on the unipolar electrogram. Conclusion The “QS” morphology of atrial wave on unipolar electrogram appears to represent a reliable marker in identification of successful ablation target of focal AT,with a high sensitivity and specificity.
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During catheter ablation of atrial fibrillation, ablation within the pulmonary veins is undesirable due to the risk of pulmonary venous stenosis and the possibility of leaving residual cuffs of arrhythmogenic tissue proximal to the ablation lesion set. An extra‐ostial pulmonary vein isolation strategy may circumvent these limitations, but achieving electrical isolation can be technically challenging, even with the use of saline‐irrigated radiofrequency energy technology. This report describes the successful use of epicardial radiofrequency ablation in a patient in whom endocardial irrigated radiofrequency ablation failed to achieve extra‐ostial pulmonary vein isolation. (J Cardiovasc Electrophysiol, Vol. 14, pp. 663‐666, June 2003)
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The purpose of this study was to determine the characteristics of the unipolar electrogram that are most helpful in predicting successful radiofrequency ablation of accessory pathways.The unipolar electrogram was analyzed at 185 ablation sites in 53 patients; 94 attempts were directed at the site of earliest atrial activation ("atrial group") and 91 at the site of earliest ventricular activation ("ventricular group"). The electrogram was analyzed for several features, including pattern ("QS" or "initial R"). Unipolar pattern: Overall, a "QS" pattern was seen at 55% of unsuccessful, 75% of temporarily successful, and 90% of permanently successful sites. For the atrial group, the respective frequencies were 53%, 77%, and 92%, and for the ventricular group, 57%, 73%, and 86%. The difference in pattern distribution between unsuccessful and permanently successful sites was significant for all groups: overall, P < 0.0001; atrial group, P = 0.0005; ventricular group, P = 0.02. Absence of a "QS" pattern (i.e., "initial R") predicted a 92% chance of unsuccessful ablation. Additional features: Activation times were significantly shorter at permanently successful than at unsuccessful (P < 0.0001) or temporarily successful sites (P = 0.0002). No significant differences were found in atrial or ventricular amplitudes or in A/V ratios. Intrinsic deflection slew was lower at temporarily successful sites (P = 0.03 vs all other sites).Ablation at sites revealing an "initial R" pattern (i.e., absent "QS") is very unlikely to be successful. Activation time is shorter at successful sites. These features are equally applicable when mapping the atrial potential as when mapping the ventricular potential.
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BACKGROUND During the extensive encircling pulmonary vein (PV) isolation (EEPVI) for atrial fibrillation (AF), it is crucial to recognize whether or not a sufficient lesion was created by an ablation in each ablation site. The local electrogram (EG)-based criteria to predict a sufficient local lesion formation, however, remain to be established. This study was performed to define local EG-based criteria for the local lesion formation during the EEPVI for AF. METHODS Among 31 patients (pts) with AF who had successful EEPVI during coronary sinus pacing, bipolar local EGs at 2271 ablation sites (73+/-19 sites/pt, posterior wall (PW) of the left atrium (LA)/anterior LA-PV junction=976/1295 sites) before and after energy delivery were reviewed. In EEPVI, ipsilateral PVs, antral regions and parts of the PW of the LA were isolated as a whole by linear ablation at the PW of the LA and semi-linear ablation at the anterior LA-PV junction. Each energy application was performed with a temperature controlled mode (maximal temperature: 55 degrees Celsius, maximal output: 35 watt) and duration of 25 to 35 seconds. RESULTS After the ablation, all PVs, antral regions and parts of the PW of the LA were successfully isolated in all 31 pts (duration of each energy application: 31+/-3 sec/site, total energy application time: 37+/-10 min/pt). After the effective ablation at each site, the local EGs exhibited predominant reduction in the amplitude of positive deflection (Ap) as compared to that of negative deflection (An) (% reduction in Ap vs An: 91+/-10 vs 30+/-59%; p<0.01, Ap/An ratio before vs after ablation: 2.3+/-3.4 vs 0.3+/-0.1; p<0.01) as well as total amplitude reduction (67+/-22%) and EG widening (57+/-43%), and the morphology of the local EG changed to the ``QS” or ``rS” patterns. At 25 sites without those morphological changes, residual LA-PV conduction gaps were observed and additional ablations were required to achieve a complete EEPVI in 20 pts. CONCLUSION We propose that a morphological change of local EGs to ``QS” or ``rS” patterns with predominant attenuation of positive deflection of local EGs can reflect sufficient local lesion formation and can be one of the practical endpoints for energy delivery at each ablation site during the EEPVI.
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Paroxysmal atrial fibrillation
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