Radiofrequency Ablation Of Typical Atrial Flutter Research Articles

Prevalence of typical atrial flutter with reentry circuit posterior to the superior vena cava: Use of entrainment at the atrial roof

Upper turn-around of the reentry circuit in typical atrial flutter (AF) is classically described to be located in front of the superior vena cava (SVC), but circuits posterior to the SVC as well as lower loop reentry (LLR) involving only the lower part of the right atrium have been described. However, true prevalence of such AF circuits remains unknown. Fifty consecutive patients (46 men, 68 +/- 9 years old) undergoing radiofrequency (RF) ablation of typical counter-clockwise AF were prospectively investigated. Prior to RF deliverance, AF was entrained by pacing 10 ms shorter than the AF cycle length (AFCL). Post-pacing interval (PPI) at the cavotricuspid isthmus (CTI) and at the atrial roof (AR)-between SVC and the high tricuspid annulus-were determined. AR was considered to be part of the AF circuit when local PPI-AFCL was < or =20 or 30 ms or, in case of long PPI at the CTI isthmus, if difference between AR-PPI and CT-PPI was < or =10 ms. In 47 patients, CTI-PPI-AFCL was < or =30 ms (94%). Among them, AR-PPI-AFCL was >30 ms in 12 cases (25%). In the remaining three patients, AR-PPI-AFCL did not exceed CTI-PPI-AFCL by more than 10 ms. In 42 patients, CTI-PPI-AFCL was < or =20 ms (84%). Among them, AR-PPI-AFCL was >20 ms in 16 cases (39%). In the remaining eight patients, AR-PPI-AFCL was more than 10 ms longer than CTI-PPI-AFCL in only one instance. Taken together, AR PPI was >20 or >30 ms longer than AFCL or >10 ms longer than CTI PPI when prolonged in 17 (34%) and 12 patients (24%), respectively. In around a quarter to one-third of patients referred for RF ablation of typical AF, the atrial roof is not part of the circuit, thus they may present a 'posterior' variant of the typical counter-clockwise AF reentry circuit.

The Electroanatomic Characteristics of the Cavotricuspid Isthmus: Implications for the Catheter Ablation of Atrial Flutter

Radiofrequency ablation (RFA) of typical AFL is sometimes difficult because of the poor electroanatomic approach to the cavotricuspid isthmus (CTI). The aim of this study was to correlate the anatomy of the CTI between contact mapping (NavX) and right atrial angiography (RAG), and to investigate the impact of the electroanatomic characteristics of the CTI on the RFA of typical atrial flutter (AFL). One hundred patients with typical AFL undergoing RFA were studied. The image-guided group consisted of 50 consecutive patients with the guidance of NavX. NavX geometry and RAG were performed to investigate the morphology of the CTI. The bipolar voltages of the CTI were collected during sinus rhythm by a NavX. The control group consisted of 50 consecutive patients with the guidance of conventional fluoroscopy. There was a good correlation between the angiography and NavX for the anatomy of the CTI. The pouch type had a longer length of CTI than the flat type (33.4 +/- 5.0 vs 22.6 +/- 8.4 mm, P < 0.0001) and deeper depth than the concave type (6.5 +/- 2.2 vs 3.7 +/- 0.8 mm, P < 0.0001) on the angiography. The pouch-type CTI had a longer ablation time and larger pulses of RFA than the other two types. The control group had a longer ablation time, fluoroscopy time, and larger pulses of RFA than image-guided group. The 3-D mapping system provided a good reconstruction of CTI, which may help in the RFA in patients with a complex anatomy of the CTI.

Double potentials along the ablation line as a guide to radiofrequency ablation of typical atrial flutter

OBJECTIVESThe purpose of this study was to determine the characteristics of double potentials (DPs) that are helpful in guiding ablation within the cavo-tricuspid isthmus.BACKGROUNDDouble 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.METHODSRadiofrequency 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.RESULTSDouble 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 (DP1-2interval) <90 ms was always associated with a local gap, whereas a DP1-2interval ≥110 ms was always associated with local block. When the DP1-2interval 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 DP1-2interval ≥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.CONCLUSIONSDetailed 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.