Cavotricuspid isthmus is constantly a zone of slow conduction: Data from ultra‐high‐resolution mapping

Abstract

Background Whether cavotricuspid isthmus (CTI) is a region of conduction slowing during typical flutter has been discussed with conflicting results in the literature. We aimed to evaluate conduction velocity (CV) along the different portions of the typical flutter circuit with a recently proposed method by means of ultra‐high‐resolution (UHR) mapping. Methods Consecutive patients referred for typical atrial flutter (AFL) ablation underwent UHR mapping (Rhythmia, Boston Scientific). CVs were measured in the CTI as well as laterally and septally, respectively, from its lateral and septal borders. Results A total of 33 patients (mean age: 65 ± 13 years; right atrial volume: 134 ± 57 mL) were mapped either during ongoing counterclockwise (n = 25), or clockwise (n = 3) AFL (mean cycle length: 264 ± 38 ms), or during coronary sinus pacing at 400 ms (n = 1), 500 ms (n = 1), or 600 ms (n = 3). A total of 13 671 ± 7264 electrograms were acquired in 14 ± 9 min. CTI CV was significantly lower (0.56 ± 0.18 m/s) in comparison with the lateral CV (1.31 ± 0.29 m/s; P < .0001) and the septal border CV of the CTI (1.29 ± 0.31 m/s; P < .0001). Conclusion UHR mapping confirmed that CTI CV was systematically twice lower than atrial conduction velocities outside the CTI.

Comparison of clockwise and counterclockwise right atrial flutter using high‐resolution mapping and automated velocity measurements

“…The same study found that CV in the CTI was significantly slower than that in the septum (p < .05). 31 More recently, Bun's use of ultra-HD mapping confirmed that CTI CVs were constantly twofold slower than atrial conduction velocities outside the CI, 32 which agrees with our results despite some differences concerning the slowdown location inside the CTI.…”

Treatment of atrial tachycardia arising after superior transseptal approach mitral valve surgery: Insights from ultra‐high‐density mapping to prevent atrioventricular block

“…In this study, slow conduction was observed near the 1 o'clock position of the tricuspid annulus in all cases with the exception of Patient 8. Previous report demonstrated CTI was a zone of slow conduction in AFL patients without prior cardiac surgery 10 . In nine of the 10 cases in this study, the slow conduction around the tricuspid annulus in STA‐AT were observed at the 1 o'clock of the tricuspid annulus, not CTI.…”

“…Previous report demonstrated CTI was a zone of slow conduction in AFL patients without prior cardiac surgery. 10 In nine of the 10 cases in this study, the slow conduction around the tricuspid annulus in STA-AT were observed at the 1 o'clock of the tricuspid annulus, not CTI. Therefore, it was considered that the mechanism of peri-tricuspid STA-ATs would be different from that of typical AFLs without prior cardiac surgery.…”

Does Unidirectional Block Exist after a Radiofrequency Line Creation? Insights from Ultra-High-Density Mapping (The UNIBLOCK Study)

“…The relatively limited number of patients included in this multicenter prospective study can be explained by the additional cost associated with the use of UHD mapping system compared to the standard approach, which limited inclusions of patients. For this reason, studies using UHD for CTI-dependent flutter usually include small populations [ 22 , 23 , 24 ]. Furthermore, activation mapping is more time-consuming (mean acquisition time 6.8 ± 5 min per map), in comparison with differential site pacing technique.…”