The deeper the pouch is, the longer the radiofrequency duration and higher the radiofrequency energy needed—Cavotricuspid isthmus ablation using intracardiac echocardiography

Abstract

BackgroundThe aim of this study was to explore whether the pouch depth influenced the radiofrequency (RF) duration and total delivered RF energy for cavotricuspid isthmus (CTI) ablation and define the cutoff value for a deep pouch‐specified ablation strategy.MethodsThis study included 94 atrial fibrillation (AF) patients (56 males, age 68 ± 8.0 years). With intracardiac echocardiography, the isthmus length and pouch depth were precisely measured. After a standard AF ablation, all patients underwent the CTI ablation along the lateral isthmus. If bidirectional block could not be achieved, the ablation catheter was deflected more than 90 degrees to ablate inside the pouch (knuckle‐curve ablation).ResultsSeventy‐two patients (76.6%) had a sub‐Eustachian pouch. Bidirectional block could be achieved in all patients. By a univariate logistic regression analysis, only the pouch depth was significantly correlated with the RF duration (P = .005) and RF energy (P = .006). A multivariate logistic regression analysis also revealed the pouch depth was the sole factor that influenced the RF duration (P = .001) and RF energy (P = .001). Among the 72 patients, 21 patients needed a knuckle‐curve ablation. Using a receiver operating characteristic curve, the optimal cutoff value of the pouch depth for a knuckle‐curve ablation was 3.7 mm with a sensitivity of 90% and specificity of 69%.ConclusionsThe sub‐Eustachian pouch depth was the sole factor that influenced the RF duration and energy in the CTI ablation. If the pouch was deeper than 3.7 mm, a deep pouch‐specified ablation strategy would be needed.

Impact of Cavotricuspid Isthmus Anatomy on the Ablation Index For Successful First-Pass Typical Atrial Flutter Ablation

“…In this study, CTI of less than 4.1 mm depth was an independent predictor for the first-pass success of CTI ablation. This cut-off value is similar to the <3.9 mm CTI depth necessary for knuckle curve ablation reported by Shimizu et al [13]. Consistent with a previous report, a lower first-pass success rate and longer procedural time were observed in the concave CTI cases.…”

“…The widely spaced double potential was also confirmed. If incomplete conduction block was suspected near the IVC, the ablation catheter would be deflected by more than 90 ° to ablate the interior of the pouch (Figure 1) [13].…”

Catheter inversion during cavotricuspid isthmus catheter ablation: The new shaft visualization catheter reduces fluoroscopy use

“…The usage of ICE enabled direct visualization and a detailed assessment of the CTI anatomy. The ICE permitted to assess real contact between the tissue and the tip catheter, to improve the precision of the RF line with a merged isthmus and continuous monitoring of the pericardium and to prevent the “steam pop” showing the increased bubbles production during RF before that steam pop occurred 18,19 . Furthermore, anatomic CTI variations represented by the presence of a flat isthmus, pouch, long CTI, and prominent Eustachian ridge/valve have been shown to be the factors related to a longer RF duration 20 .…”

A cavotricuspid isthmus pouch revealed to be a breakout site for gap conduction of recurrent common atrial flutter

“…Shimizu et al reported that the depth of the pouch was related to the RF duration and energy required to create a CTI block line, and the usefulness of knucklecurve ablation inside the pouch. 2 The use of intracardiac echocardiography is reported to be useful to detect CTI pouch in difficult cases. 3 In our case, we could not notice the existence of the prominent CTI pouch and failed to create a complete CTI block line during the first session.…”

“…A CTI pouch is mainly seen in the medial side of the CTI 1 and is known to complicate the creation of a CTI block line. Shimizu et al reported that the depth of the pouch was related to the RF duration and energy required to create a CTI block line, and the usefulness of knuckle‐curve ablation inside the pouch 2 . The use of intracardiac echocardiography is reported to be useful to detect CTI pouch in difficult cases 3 .…”