Reentry mechanisms and ablation of ECG-typical atrial flutters involving the cavo-tricuspid isthmus and the proximal coronary sinus.

Reentry circuits of a rare typical atrial flutter (AFL) involving the cavo-tricuspid isthmus (CTI) and proximal coronary sinus (CS) are described based on electrophysiological data and effects of radiofrequency (RF). Twelve patients with ECG-typical AFL in whom entrainment demonstrated that CTI and proximal CS were both part of the circuit were included. Initial RF target was CTI in 8 patients and proximal CS in 4. Success was defined as AFL termination/noninducibility. After CTI ablation, AFL cycle length (CL) increased in all: AFL persisted in 3, while in the other 5 AFL was interrupted but subsequently induced with the same morphology; before induction CTI bi-directional block was validated; success was obtained at the CS, targeting fragmented atrial potentials (APs). In those with first ablation at CS, AFL was interrupted in 3 with no AFL inducibility; in 1 AFL persisted with CL prolongation and was terminated at CTI. Two reentry patterns were identified: in 5 patients the inter-atrial septum as well as the mid-distal CS were outside of the circuit, while the CTI, proximal CS and Bachmann's bundle zone were inside, suggesting a left atrial component; in 1 patient electrophysiological mapping suggested an intra-CS circuit component. RF was successful in all without recurrence. Electrophysiological mapping and RF effects suggest a continuum between the CTI and proximal CS in rare cases with ECG-typical AFL. RF inside the proximal CS, targeting fragmented APs, should be considered in any patient in whom CTI ablation failed to interrupt a typical AFL.

De Sisti A ，Tonet J ，Márquez MF ，Amara W ，Broustet H ，Touil F ，Hidden-Lucet F ... -  《-》

Simple and efficient identification of conduction gaps in post-ablation recurring atrial flutters.

Laurent G ，De Chillou C ，Bertaux G ，Poull IM ，Martel A ，Andronache M ，Fromentin S ，Fraison M ，Gonzalez S ，Pierre FS ，Aliot E ，Wolf JE ... -  《EUROPACE》

Is proximal coronary sinus involved in the circuit in some cases of ECG "typical" atrial flutter?

It is commonly conceived that coronary sinus (CS) participates in atrial flutter (AFL) circuit but limited to the fibers surrounding its ostium. We evaluated the involvement of proximal CS in typical AFL. Twenty AFL patients underwent entrainment mapping using postpacing interval minus AFL cycle length (PPI-AFL CL) including CS where a decapolar catheter was positioned with proximal bipole 1 cm from the ostium. We compared patients with proximal CS within the circuit (group 1, PPI-AFL CL ≤ 20 ms + concealed entrainment) and those without (group 2, PPI-AFL CL > 20 ms). Group 1 patients were older, 77.5 ± 4 vs 71 ± 12 years (P < 0.05). No difference was found in AFL CL, PPI-AFL CL at cavotricuspid isthmus (CTI) entry, plateau, and septal site. Group 1 patients had shorter PPI-AFL CL at proximal CS (9 ± 3 vs 40 ± 15 ms; P < 0.001) and fragmented mesodiastolic CS atrial potentials (APs) (106 ± 27 vs 58.5 ± 22 ms; P < 0.001). A mid-septal unexcitable scar was found in five of eight group 1 patients vs one of 12 group 2 patients (P < 0.05). All were ablated at CTI. A patient had AFL recurrence and underwent a second attempt: PPI-AFL CL was 60 ms at CTI entry and less than or equal to 20 ms at septal CTI and proximal CS; AFL was terminated 1 cm inside CS, applying RF at a fragmented AP. Proximal CS appears to be involved in a substantial subset of typical AFL patients, in whom advanced age, fragmented CS APs, and the presence of right atrial scar are prevalent. Proximal CS might be considered as an un-"innocent by-stander," but able, in rare cases, to generate a second AFL circuit.

De Sisti A ，Andronache M ，Damiano P ，Eschalier R ，Font M ... -  《-》

Radiofrequency ablation of coronary sinus-dependent atrial flutter guided by fractionated mid-diastolic coronary sinus potentials.

Tonet J ，De Sisti A ，Amara W ，Frank R ，Hidden-Lucet F ... -  《-》

Reentry within the cavotricuspid isthmus: an isthmus dependent circuit.

Yang Y ，Varma N ，Keung EC ，Scheinman MM ... -  《PACE-PACING AND CLINICAL ELECTROPHYSIOLOGY》