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

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

“…CS ablation sites were located 1 to 4 cm from ostium. In a subgroup of five patients, a possible re‐entry pattern was evident after CTI ablation: the CTI entry and mid‐IAS septum were without the circuit, while the septal CTI, proximal CS, and high‐IAS were inside. No recurrence of ablated arrhythmias occurred during a mid‐term follow‐up.…”

“…The ensemble of these reports is not homogeneous [19][20][21][22][23][24][30][31][32][33][34] and various re-entry patterns can be conceived in these "CS AFLs." The Eustachian ridge is not a fixed barrier, permitting a circuit re-entry in a dissociated CTI.…”

“…19,20,[30][31][32] CS ostium can also be implicated in the reentry, associated or not with CTI-dissociated areas 19,20,23 as well as proximal CS. 21,22,34 A point in common, among these studies, is the presence of fragmented low-voltage APs variably and extensively located between septal CTI, CS ostium, and proximal CS (all sites within the circuit at entrainment maneuvers at RF successful sites). Fibrosis [19][20][21][22][23][24][30][31][32][33][34] due to age, structural HD, previous CTI RF ablation, and LA enlargement appears to favor these AFLs.…”

“…Some authors described, or at least suggested, a proximal CS and maybe left atrium (LA) involvement in the circuit of some cases of typical AFL or iatrogenic recurrent AFL after successful CTI radiofrequency (RF) ablation, implying a nonexclusive CTI location of a part of the circuit. Globally, these AFLs are considered episodic or very uncommon.…”

“…Anisotropic conduction [16][17][18] due to cross-over and interlacing trabeculae at this site could occur in this area and leads to a conduction delay of the lower CTI septum and maybe of the CS close to it. Some authors described, or at least suggested, a proximal CS and maybe left atrium (LA) involvement in the circuit of some cases of typical AFL or iatrogenic recurrent AFL after successful CTI radiofrequency (RF) ablation, [19][20][21][22][23] implying a nonexclusive CTI location of a part of the circuit. Globally, these AFLs are considered episodic or very uncommon.…”