CLINICAL STUDY: ELECTROPHYSIOLOGY
Double potentials along the ablation line as a guide to radiofrequency ablation of typical atrial flutter
Hiroshi Tada, MDa,
Hakan Oral, MDa,
Christian Sticherling, MDa,
Steven P. Chough, MDa,
Robert L. Baker, MDa,
Kristina Wasmer, MDa,
Frank Pelosi, Jr, MDa,
Bradley P. Knight, MD, FACCa,
S. Adam Strickberger, MD, FACCa and
Fred Morady, MD, FACCa
a Division of Cardiology, Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan, USA
Manuscript received October 13, 2000;
revised manuscript received May 9, 2001,
accepted May 22, 2001.
Reprint requests and correspondence: Dr. Fred Morady, Division of Cardiology, B1F245, University of Michigan Health System, 1500 East Medical Center Drive, Ann Arbor, Michigan 48109-0022
fmorady{at}umich.edu
 |
Abstract
|
|---|
OBJECTIVES
The purpose of this study was to determine the characteristics of double potentials (DPs) that are helpful in guiding ablation within the cavo-tricuspid isthmus.
BACKGROUND
Double potentials have been considered a reliable criterion of cavo-tricuspid isthmus block in patients undergoing radiofrequency ablation of typical atrial flutter (AFL). However, the minimal degree of separation of the two components of DPs needed to indicate complete block has not been well defined.
METHODS
Radiofrequency ablation was performed in 30 patients with isthmus-dependent AFL. Bipolar electrograms were recorded along the ablation line during proximal coronary sinus pacing at sites at which radiofrequency ablation resulted in incomplete or complete isthmus block.
RESULTS
Double potentials were observed at 42% of recording sites when there was incomplete isthmus block, compared with 100% of recording sites when the block was complete. The mean intervals separating the two components of DPs were 65 ± 21 ms and 135 ± 30 ms during incomplete and complete block, respectively (p < 0.001). An interval separating the two components of DPs (DP1-2 interval) <90 ms was always associated with a local gap, whereas a DP1-2 interval  110 ms was always associated with local block. When the DP1-2 interval was between 90 and 110 ms, an isoelectric segment within the DP and a negative polarity in the second component of the DP were helpful in indicating local isthmus block. A DP1-2 interval 90 ms with a maximal variation of 15 ms along the entire ablation line was an indicator of complete block in the cavo-tricuspid isthmus.
CONCLUSIONS
Detailed analysis of DPs is helpful in identifying gaps in the ablation line and in distinguishing complete from incomplete isthmus block in patients undergoing radiofrequency ablation of typical AFL.
|
Abbreviations and Acronyms
| | AFL | = atrial flutter | | DP(s) | = double potential(s) | | DP1–2 interval | = interval separating the two components of double potentials |
|
A corridor of parallel double potentials (DPs) along the ablation line has been recognized to be an indicator of complete isthmus block in patients undergoing radiofrequency catheter ablation of typical atrial flutter (AFL) (1,2). However, DPs may also be present along the ablation line when isthmus block is incomplete (3,4). The minimal degree of separation needed to indicate complete isthmus block has not been well defined. In addition, it is possible that other characteristics of DPs, such as polarity or the presence of an isoelectric segment within the DPs, might also be helpful in distinguishing complete from incomplete isthmus block. The purpose of this prospective study was to determine the characteristics of DPs that are helpful in identifying gaps in the ablation line and in distinguishing complete from incomplete isthmus block during radiofrequency catheter ablation of typical AFL.
|
Methods
|
|---|
Characteristics of subjects.
Among 50 consecutive patients who underwent radiofrequency catheter ablation of isthmus-dependent AFL at the University of Michigan Medical Center, 30 had recordings obtained along the ablation line both during incomplete isthmus block and after complete isthmus block had been achieved. These 30 patients (23 men and 7 women, mean age 58 ± 13 years, ± SD) served as the subjects of this study. Of the patients, 4 had coronary artery disease, 3 had idiopathic dilated cardiomyopathy and 23 had no structural heart disease.
Electrophysiologic procedure.
All patients provided written, informed consent before the electrophysiologic procedure. Three venous sheaths were inserted into a femoral vein for vascular access. A 7F duo-decapolar halo catheter (2-mm spacing between electrodes of each bipole; 20-2-2-2-2-2-2-25-25-25-mm spacing between pairs of electrodes, Daig Corp., Minnetonka, Minnesota) was positioned along the tricuspid annulus with the distal bipole of the halo catheter within the proximal portion of the coronary sinus (Fig. 1). A 7F quadripolar catheter (EP Technologies Inc., San Jose, California) was positioned within the proximal coronary sinus for pacing. A 7F quadripolar catheter with a deflectable tip, 4-mm distal electrode, 2-5-2-mm interelectrode spacing and a thermistor embedded in the distal electrode (EP Technologies Inc.) was used for mapping the isthmus and delivering radiofrequency energy.
View larger version (166K):
[in this window]
[in a new window]
|
Figure 1 A 45° left anterior oblique fluoroscopic view of catheter positions during atrial flutter ablation (ABL) is shown. A duo-decapolar halo catheter is positioned around the tricuspid annulus and along the cavo-tricuspid isthmus. Electrode pairs of the halo catheter are labeled E1 to E9. Note that E1 and E2 are positioned just lateral to the intended ABL line. A quadripolar electrode catheter is positioned within the coronary sinus (CS) for pacing. The ABL catheter is positioned at the intended ABL line. The recordings displayed in Figures 2 through 5 were obtained with the catheters positioned as shown in this figure.
|
|
View larger version (28K):
[in this window]
[in a new window]
|
Figure 2 Recordings during coronary sinus (CS) pacing before (left and middle) and after (right) complete isthmus block are shown. Displayed are leads II, III and V1, electrograms recorded by the ablation catheter (Abl), electrograms recorded at E9 through E1 of the halo catheter, an electrogram recorded in the CS and the stimulus (St) channel. The arrows in the electrograms recorded by the Abl point to the components of the double potentials (DPs). The Abl was positioned at exactly the same site in all three panels. (Left) After several applications of radiofrequency energy along the ablation line, the interval separating the two components of DPs (DP1-2) is 61 ms, and there is incomplete block. (Middle) After an additional application of radiofrequency energy, the DP1-2 interval increases to 96 ms, but isthmus block is still incomplete. (Right) After a final application of radiofrequency energy, the DP1-2 interval lengthens to 124 ms, and now there is complete block, based on both the atrial activation sequence in E1 to E9 and a change in the initial polarity of E1 and E2 from positive to negative. Note that when the DP1-2 interval was 96 ms, the segment separating the two components of the DP was not isoelectric, providing further evidence that there was a persistent gap in the ablation line. On the transition to complete block, the segment with the DP became isoelectric.
|
|
Bipolar electrograms were always recorded with the distal electrode serving as the cathode, filtered at settings of 30 to 500 Hz and recorded digitally (EPMed Systems, Inc., Mount Arlington, New Jersey). Electrograms were analyzed off-line at a gain setting of 0.1 to 0.2 mV/cm and at a sweep speed of 100 to 200 mm/s. Pacing was performed with a stimulator (Model EP-3 Clinical Stimulator, EPMed Systems, Inc.) at twice the diastolic threshold and with a pulse width of 2 ms.
Radiofrequency ablation was performed during AFL in 16 patients who presented with AFL (mean cycle length 248 ± 26 ms) or during coronary sinus pacing at a cycle length of 500 to 600 ms in the 14 patients who were in sinus rhythm. Under fluoroscopic guidance, individual contiguous applications of radiofrequency energy were delivered to create a line of block in the cavo-tricuspid isthmus. The power was automatically adjusted to maintain a target temperature of 60°C at the electrode-tissue interface. Each application of energy was 45 to 60 s in duration.
The end point of the procedure was complete isthmus block in the clockwise and counterclockwise directions. This end point was attained in all patients in this study. The criteria used to identify complete block consisted of an atrial activation sequence around the tricuspid annulus consistent with complete block (5–11), negative initial polarity of the electrograms recorded just lateral to the ablation line during coronary sinus pacing (12) and the presence of DPs along the entire ablation line (Fig. 2) (1,2). These criteria had to be present before and during infusion of 2 µg/min of isoproterenol (13). In a previous study, complete isthmus block was associated with DPs separated by an interval ranging from 60 to 190 ms during pacing at the posterolateral right atrium (1). However, one of the goals of this study was to determine whether there is a critical degree of separation between the two components of a DP that distinguishes incomplete from complete isthmus block. Therefore, the degree of separation within DPs was not used as an end point in this study.
During a mean of 12 ± 4 months of follow-up, none of the patients in this study had a recurrence of AFL. Eleven of the patients continued treatment with a class I or III antiarrhythmic drug to prevent recurrences of atrial fibrillation.
Analysis of electrograms.
In accordance with the criteria used to select the subjects in this study, complete isthmus block was preceded by incomplete block in all patients in this study. Incomplete block, also referred to as slowing of transisthmus conduction, was defined as a measurable delay in conduction across the cavo-tricuspid isthmus, in the absence of criteria for complete isthmus block. To ensure that the electrograms before and after a change in transisthmus conduction were being compared at exactly the same recording site, the analysis was limited to the sites at which an application of radiofrequency energy resulted in measurable slowing of conduction or complete block. The electrograms recorded along the ablation line during incomplete and complete isthmus block were analyzed post hoc by two observers. In the 14 patients who were in sinus rhythm at the onset of the procedure, the electrograms recorded along the ablation line were compared before and after the onset of incomplete isthmus block. In addition, in all 30 patients, the electrograms recorded along the ablation line were compared just before and after the transition from incomplete to complete isthmus block.
The interval separating the two components of a DP (DP1-2 interval) was measured with electronic calipers from the peak of the first component of the DP to the peak of the second component. In addition, the segment separating the two components of DPs was classified according to whether or not it was isoelectric (Fig. 2). The morphology of the second component of DPs was characterized by terminology used to describe QRS complexes on the surface electrocardiogram (Fig. 3).
View larger version (21K):
[in this window]
[in a new window]
|
Figure 3 Double potentials (DPs) recorded along the ablation line in the cavo-tricuspid isthmus during coronary sinus pacing are depicted. Shown are examples of DPs in which the second component (larger bold arrows) had either a negative or positive polarity. The morphology of the second component was characterized by terminology used to describe QRS complexes. The smaller arrows indicate the first component of the DPs. St = stimulus channel.
|
|
Statistical analysis.
Continuous variables are reported as the mean ± 1 SD and were compared using the Student t test. Categorical variables were compared by chi-square analysis or the Fisher exact test. A p value <0.05 was considered statistically significant.
|
Results
|
|---|
DP1-2 interval.
A DP was recorded along the ablation line at 25 (42%) of 58 sites at which an application of radiofrequency energy resulted in slowing of transisthmus conduction and at each of 30 sites (100%) at which an application of radiofrequency energy resulted in complete isthmus block (p < 0.001). The mean DP1-2 interval was 65 ± 21 ms (range 35 to 103 ms) when there was incomplete block, compared with 135 ± 30 ms (range 95 to 198 ms) when there was complete block (p < 0.001) (Fig. 4).
View larger version (18K):
[in this window]
[in a new window]
|
Figure 4 The intervals separating the two components of double potentials (DP1-2) recorded along the ablation line during coronary sinus pacing before and after complete block in the cavo-tricuspid isthmus are shown. Also depicted are the mean values ± SD. Note that a DP1-2 interval <90 ms was always associated with incomplete block and a DP1-2 interval 110 ms was always associated with complete block. Although there were 30 patients in this study, the sample size during incomplete block was 25 patients, because a DP was not always present during incomplete isthmus block.
|
|
Isoelectric segments within DPs.
At the 25 sites at which a DP was recorded when there was incomplete isthmus block, the segment separating the two components of the DP was isoelectric at 5 (20%). In contrast, at the 30 sites at which a DP was recorded on the transition to complete isthmus block, the segment separating the two components of the DP was isoelectric at 25 (83%, p < 0.001) (Fig. 2).
Polarity.
The initial polarity of the second component of DPs was mainly negative (Qr, QS or rSr pattern) in 11 (44%) of 25 DPs recorded when there was incomplete block and in 27 (90%) of 30 DPs recorded on the transition to complete isthmus block (p < 0.001) (Fig. 5).
View larger version (23K):
[in this window]
[in a new window]
|
Figure 5 An interval separating the two components of double potentials (DP1-2) of 94 ms was recorded along the ablation (Abl) line in the cavo-tricuspid isthmus during coronary sinus (CS) pacing, after several applications of radiofrequency energy. The DP1-2 interval is between 90 and 110 ms, which is equally likely when block is incomplete or complete. In this case, the fractionated, low-amplitude electrogram within the DP, along with the predominantly positive polarity of the second component of the DP, suggests that block is incomplete. The presence of incomplete block is confirmed by the atrial activation sequence in E1 to E8 and by the positive initial polarity of E1 and E2. Without moving the ablation catheter, an additional application of radiofrequency energy was delivered, and the DP1-2 interval increased to 132 ms, a value always associated with complete isthmus block. Complete block was confirmed by the atrial activation sequence in the halo catheter and by a change to negative initial polarity of E1 and E2. St = stimulus channel.
|
|
Sensitivity and specificity of DP criteria.
The sensitivity, specificity and predictive accuracy of DP criteria for complete cavo-tricuspid isthmus block are shown in Table 1. There were no significant differences in sensitivity, specificity or positive or negative predictive values among these criteria.
DPs along the ablation line after complete isthmus block.
The entire ablation line was mapped after complete block in the cavo-tricuspid isthmus was achieved. The DPs were present along the entire ablation line, and at all sites in all patients, the DP1-2 interval was >90 ms. The mean variation in the DP1-2 interval at multiple sites along the ablation line was 5 ± 1 ms, with a maximal variation of 15 ms.
|
Discussion
|
|---|
Major findings.
The results of this study demonstrate that DPs recorded along the ablation line in the cavo-tricuspid isthmus during coronary sinus pacing are helpful in identifying gaps in the ablation line, but only when the specific characteristics of the DPs are analyzed. Patients were selected for inclusion in this study if their block was incomplete after an initial series of applications of radiofrequency energy in the cavo-tricuspid isthmus. In these patients, a local DP1-2 interval 110 ms was found to be a reliable indicator of local block, and a DP1-2 interval <90 ms was found to be a reliable indicator of a local gap. When the DP1-2 interval was between 90 and 110 ms, the recording site was equally likely to be a site of local block or a gap, and other characteristics of the DP were found to be helpful in making this distinction. When the segment between the two components of the DP was not isoelectric, or when the polarity of the second component of the DP was positive, the recording site was likely to be at or very close to a gap in the ablation line.
The results of this study also demonstrate that the DP1-2 intervals recorded along the ablation line during coronary sinus pacing can serve as an end point for the ablation procedure. A DP1-2 interval >90 ms at all points along the ablation line and maximal variation  15 ms in the DP1-2 intervals recorded along the ablation line are reliable indicators that complete bidirectional block in the cavo-tricuspid isthmus has been achieved.
Degree of splitting within DPs.
Using electroanatomic mapping in a group of eight patients, a recent study demonstrated that when there is a gap in the ablation line in the cavo-tricuspid isthmus, the DP1-2 interval varies according to the proximity of the recording site to the gap. When the recording site was adjacent to the gap, the width of the DP was 62 ± 16 ms, and at recording sites farther away from the gap, the DP width was 123 ± 34 ms (3).
In the present study, the analysis of DPs was limited to sites at which an application of radiofrequency energy resulted in either a measurable slowing of conduction across the cavo-tricuspid isthmus or complete isthmus block. Therefore, these sites were very likely to be within or in close proximity to a gap in the ablation line. When there was incomplete isthmus block, the mean DP1-2 interval was found to be 65 ± 21 ms, remarkably similar to the mean value of 62 ± 16 ms reported in a previous study (3). However, the present study extends the findings of the previous study (3) by comparing the DP1-2 interval at the same recording site before and after complete isthmus block and demonstrating that a DP1-2 interval <90 ms always indicates the persistence of a gap in the ablation line, whereas a DP1-2 interval 110 ms always indicates the absence of a gap at that recording site. Because the DP1-2 interval lengthens as the distance of the recording site from a gap increases (3), a DP1-2 interval 110 ms might be present along an ablation line, even when block is incomplete, if the recording site is not near a gap.
Isoelectric interval within DPs.
In this study, the DP1-2 interval was found to be isoelectric in most instances of complete isthmus block, and usually it contained fractionated and low-amplitude electrical activity when the block was incomplete. Low-amplitude, fractionated activity recorded during ventricular tachycardia is thought to represent slow conduction through diseased tissue in a portion of the re-entry circuit (14). In a similar fashion, it is possible that the low-amplitude, fractionated activity recorded within DPs in the cavo-tricuspid isthmus is attributable to slow or discontinuous conduction, or both, through a gap in the ablation line.
Polarity of DPs.
A previous study found that the initial polarity of the electrograms recorded lateral to the ablation line during coronary sinus pacing changes from positive to negative on the transition from incomplete to complete isthmus block (12). In this study, the initial polarity of the second component of the DPs recorded at the gap in the ablation line was also found to usually become negative on elimination of the gap. This change in polarity may be explained by a reversal in the direction of the activation wave front across the distal bipole of the ablation catheter on transition from incomplete to complete isthmus block.
Study limitations.
A limitation of this study is that the analysis of DPs was limited to sites at which an application of radiofrequency energy had a measurable effect on transisthmus conduction. Mapping of the entire ablation line before and after an application of radiofrequency energy would have made it very difficult to compare electrograms at exactly the same recording site. Therefore, the results of this study cannot be applied to DPs that are recorded at sites along the ablation line that are distant from a gap.
A second limitation of this study is that the clinically available end points that are used to identify complete isthmus block, including the atrial activation sequence around the tricuspid annulus during pacing in the coronary sinus and at the posterolateral right atrium, may not accurately distinguish a line of complete block from a line with a small gap that allows very slow conduction across the isthmus. However, the absence of recurrent AFL during follow-up in all of the patients in this study suggests that even if cavo-tricuspid isthmus block was incomplete sometimes, the degree of persistent conduction across the isthmus was not clinically important.
A third limitation is that only the DPs recorded during pacing from the coronary sinus were analyzed in this study. Therefore, the specific criteria described in this study may not apply to DPs that are recorded along an ablation line during pacing from the posterolateral right atrium. However, the DP criteria described in this study were indicative of complete bidirectional isthmus block; therefore, pacing from the posterolateral right atrium to confirm block in the counterclockwise direction is not necessary when using these criteria.
Conclusions.
During conventional radiofrequency ablation in the cavo-tricuspid isthmus, the first series of radiofrequency applications across the isthmus often do not result in complete block. In fact, this was the case in over half of the 50 patients with isthmus-dependent AFL who were screened for this study. Therefore, an awareness of the local electrogram characteristics that identify a gap in the ablation line should facilitate a successful outcome of the ablation procedure. Additional applications of radiofrequency energy are appropriate, not only at sites at which the electrogram is single instead of double, but also at sites where the DP1-2 interval is <90 ms. When the DP1-2 interval is between 90 and 110 ms, an additional application of radiofrequency energy is appropriate if there is fractionated, low-amplitude activity in the segment between the two components of the DP, or if the second component of the DP is positive in polarity. If the local DP1-2 interval is 110 ms, the recording site is very unlikely to be at a gap, and an additional application of radiofrequency energy is not needed at that site.
When the DP1-2 interval is >90 ms at all points along the ablation line during coronary sinus pacing, and when the maximal variation in the DP1-2 interval along the ablation line is 15 ms, it is likely that complete bidirectional isthmus block has been achieved. Therefore, in addition to identifying target sites for ablation, analysis of DPs also provides a reliable end point for the ablation procedure. The use of DPs as an end point for ablation in the cavo-tricuspid isthmus has potential advantages over other techniques for identifying complete block: 1) the atrial activation sequence around the tricuspid annulus is sometimes ambiguous as an indicator of complete isthmus block (10,11) and, at times, may be inaccurate, such as when there is conduction posterior to the inferior vena cava (15); and 2) the ablation line is easily mapped with the ablation catheter, obviating the need for a halo catheter or more sophisticated and expensive mapping systems, such as electroanatomic mapping (3), or noncontact mapping.
|
Footnotes
|
|---|
This study was supported in part by a grant from the Japanese Society of Cardiac Pacing and Electrophysiology and by the Don Nouse Arrhythmia Research Fund.
|
References
|
|---|
1. Shah DC, Takahashi A, Jais P, Hocini M, Clementy J, Haissaguerre M. Local electrogram-based criteria of cavo-tricuspid isthmus block. J Cardiovasc Electrophysiol. 1999;10:662–669[Medline]
2. Shah DC, Haissaguerre M, Jais P, et al. Simplified electrophysiologically directed catheter ablation of recurrent common atrial flutter. Circulation. 1997;96:2505–2508[Abstract/Free Full Text]
3. Shah DC, Haissaguerre M, Jais P, Takahashi A, Hocini M, Clementy J. High-density mapping of activation through an incomplete isthmus ablation line. Circulation. 1999;99:211–215[Abstract/Free Full Text]
4. Takahashi A, Shah DC, Jais P, Hocini M, Clementy J, Haissaguerre M. Partial cavotricuspid isthmus block before ablation in patients with typical atrial flutter. J Am Coll Cardiol. 1999;33:1996–2002[Abstract/Free Full Text]
5. Lesh MD, Van Hare GF, Epstein LM, et al. Radiofrequency catheter ablation of atrial arrhythmias: results and mechanisms. Circulation. 1994;89:1074–1089[Abstract/Free Full Text]
6. Fischer B, Haissaguerre M, Garrigues S, et al. Radiofrequency catheter ablation of common atrial flutter in 80 patients. J Am Coll Cardiol. 1995;25:1365–1372[Abstract]
7. Blanck Z, Cetta T, Sra J, et al. Catheter ablation of atrial flutter using radiofrequency current: cumulative experience in 61 patients. WMJ. 1998;97:43–48[Medline]
8. Calkins H, Leon AR, Deam AG, Kalbfleisch SJ, Langberg JJ, Morady F. Catheter ablation of atrial flutter using radiofrequency energy. Am J Cardiol. 1994;73:353–356[CrossRef][Medline]
9. Nakagawa H, Lazzara R, Khastgir T, et al. Role of the tricuspid annulus and eustachian valve/ridge on atrial flutter: relevance to catheter ablation for the septal isthmus and a new technique for rapid identification of ablation success. Circulation. 1996;94:407–424[Abstract/Free Full Text]
10. Poty H, Saoudi N, Nair M, Anselme F, Letac B. Radiofrequency catheter ablation of atrial flutter: further insights into the various types of isthmus block—application to ablation during sinus rhythm. Circulation. 1996;94:3204–3213[Abstract/Free Full Text]
11. Schwartzman D, Callans DJ, Gottlieb CD, Dillon SM, Movsowitz C, Marchlinski FE. Conduction block in the inferior vena caval-tricuspid valve isthmus: association with outcome of radiofrequency ablation of type I atrial flutter. J Am Coll Cardiol. 1996;28:1519–1531[Abstract]
12. Tada H, Oral H, Sticherling C, et al. Electrogram polarity and cavo-tricuspid isthmus block during ablation of typical atrial flutter. J Cardiovasc Electrophysiol. 2001;12:393–399[CrossRef][Medline]
13. Nabar A, Rodriguez L, Timmermans C, Smeets JLRM, Wellens HJJ. Isoproterenol infusion to evaluate resumption of conduction after atrial isthmus in type I atrial flutter. Circulation. 1999;99:3286–3291[Abstract/Free Full Text]
14. Stevenson WG, Weiss JN, Wiener I, et al. Fractionated endocardial electrograms are associated with slow conduction in human: evidence from pace-mapping. J Am Coll Cardiol. 1989;13:369–376[Abstract]
15. Scaglione M, Riccardo R, Calo L, et al. Typical atrial flutter ablation: conduction across the posterior region of the inferior vena cava orifice may mimic unidirectional isthmus block. J Cardiovasc Electrophysiol. 2000;11:387–395[Medline]
This article has been cited by other articles:
|
|
|
|
 
A. Chugh, R. Latchamsetty, H. Oral, D. Elmouchi, D. Tschopp, S. Reich, P. Igic, T. Lemerand, E. Good, F. Bogun, et al.
Characteristics of Cavotricuspid Isthmus-Dependent Atrial Flutter After Left Atrial Ablation of Atrial Fibrillation
Circulation,
February 7, 2006;
113(5):
609 - 615.
[Abstract]
[Full Text]
[PDF]
|
|
|
|
|
|
|
G. Laurent, C. De Chillou, Gér. Bertaux, I. M. Poull, A. Martel, M. Andronache, S.ép. Fromentin, M. Fraison, S.ép. Gonzalez, F.ço. S. Pierre, et al.
Simple and efficient identification of conduction gaps in post-ablation recurring atrial flutters.
Europace,
January 1, 2006;
8(1):
7 - 15.
[Abstract]
[Full Text]
[PDF]
|
|
|
|
|
|
|
C. Scharf, S. Veerareddy, M. Ozaydin, A. Chugh, B. Hall, P. Cheung, E. Good, F. Pelosi Jr, F. Morady, and H. Oral
Clinical significance of inducible atrial flutter during pulmonary vein isolation in patients with atrial fibrillation
J. Am. Coll. Cardiol.,
June 2, 2004;
43(11):
2057 - 2062.
[Abstract]
[Full Text]
[PDF]
|
|
|
|
|
|
|
G. Feld, M. Wharton, V. Plumb, E. Daoud, T. Friehling, L. Epstein, and EPT-1000 XP Cardiac Ablation System Investigators
Radiofrequency catheter ablation of type 1 atrial flutter using large-tip 8- or 10-mm electrode catheters and a high-output radiofrequency energy generator: Results of a multicenter safety and efficacy study
J. Am. Coll. Cardiol.,
April 21, 2004;
43(8):
1466 - 1472.
[Abstract]
[Full Text]
[PDF]
|
|
|
|
|
|
|
M. Andronache, C. de Chillou, H. Miljoen, I. Magnin-Poull, M. Messier, P. Dotto, D. Beurrier, T. Doan, P. Houriez, A. Bineau-Jorisse, et al.
Correlation between electrogram morphology and standard criteria to validate bidirectional cavotricuspid block in common atrial flutter ablation
Europace,
January 1, 2003;
5(4):
335 - 341.
[Abstract]
[Full Text]
[PDF]
|
|
|
|
|
|
|
F. Morady and H. Tada
Double potentials analysis as a guide to radiofrequency ablation of atrial flutter: Reply
J. Am. Coll. Cardiol.,
March 6, 2002;
39(5):
916 - 917.
[Full Text]
[PDF]
|
|
|
|
|
|
|
P. Turco, G. Stabile, A. De Simone, and B. El Jamal
Double potentials analysis as a guide to radiofrequency ablation of atrial flutter
J. Am. Coll. Cardiol.,
March 6, 2002;
39(5):
916 - 916.
[Full Text]
[PDF]
|
|
|
|
Top
Abstract
Methods