Conduction Properties of the Crista Terminalis and Its Influence on the Right Atrial Activation Sequence in Patients with Typical Atrial Flutter

Abstract

The conduction properties of the crista terminalis (CT) and its influence on the right atrial activation sequence were analyzed in 14 patients with typical atrial flutter (AF). Atrial mapping was performed with 35 points of the right atrium during typical AF and during atrial pacing performed after linear ablation of inferior vena cava-tricuspid annulus (IVC-TA) isthmus. Atrial pacing was delivered from the septal isthmus at cycle lengths of 600 ms and the tachycardia cycle length (TCL). The right atrial activation sequence and the conduction interval (CI) from the septal to lateral portion of the IVC-TA isthmus were analyzed. During AF, the conduction block line (CBL) (detected by the appearance of double potentials along the CT and craniocaudal activation on the side anterior to CT) was observed along the CT in all patients. The TCL and CI during AF were 254 +/- 19 and 207 +/- 14 ms, respectively. During pacing at a cycle length of 600 ms, the CBL was observed along the CT in four patients, however, a short-circuiting activation across the CT was observed in the remaining ten patients. The CI during pacing at 600 ms was 134 +/- 38 ms, shorter than that during AF (P < .0001). During pacing at the TCL, the CBL was observed along the CT in all patients. The presence of the CBL along the CT prevented a short-circuiting activation across the CT and resulted in the same right atrial activation as observed during AF. With the formation of the CBL, the CI significantly increased to 206 +/- 17 ms and was not different from that during AF. These data suggest that the conduction block along the CT is functional. It was presumed that presence of conduction block at the CT has some relevance to the initiation of typical AF though it was not confirmed.

Activation Patterns and Conduction Velocity in Posterolateral Right Atrium During Typical Atrial Flutter Using an Electroanatomic Mapping System

“…7,8 Thus, there may be the complication of another loop reentry, together with typical AFL rotation around the TA. Furthermore, the other loop reentry would travel across the line between the SVC and IVC in the posterolateral wall of the RA, and this has been confirmed by conventional electrophysiological methods, 9 electroanatomic mapping 10 and, recently, by noncontact mapping. 7,8 The pattern of propagation across the posterolateral RA has been studied using virtual electrograms, 8 but the conduction patterns and conduction velocity (CV) across the CT during typical AFL, as seen on actual electrograms, are not completely understood.…”

Electrophysiologic and Anatomical Characteristics of the Right Atrial Posterior Wall in Patients With and Without Atrial Flutter Analysis by Intracardiac Echocardiography

“…[4][5][6] Most former studies assumed that the localization of the transverse conduction block was the CT in AFL patients. [4][5][6][7][8][9] However, more current studies [14][15][16][17][18] using ICE or noncontact mapping systems have concluded that the conduction block occurred at the posteromedial RA (sinus venosa region) rather than on the CT. The present study also showed that the DP recording site observed in the AFL patients was located at the posterolateral RA adjacent to the posterior edge of the CT or posteromedial RA.…”

“…The prior studies [6][7][8][9]20,21 showed a rate-dependent conduction block at the posterior RA and a propensity for conduction block in AFL patients as compared with those with atrial fibrillation. 6,7,9 In the present study, the ERP of the posterior RA was also significantly longer in the AFL patients than in the control patients.…”

“…[1][2][3][4][5] The tricuspid annulus forms the anterior boundary, and the crista terminalis (CT) has been suggested as the posterior boundary. [4][5][6][7][8][9] A linear lesion between the tricuspid annulus and inferior vena cava (IVC) terminates AFL and predicts long-lasting freedom from any clinical recurrence. [10][11][12][13] Transverse conduction block also has been documented along the CT, on the basis of recording double potentials (DPs) by conventional methods.…”

“…[10][11][12][13] Transverse conduction block also has been documented along the CT, on the basis of recording double potentials (DPs) by conventional methods. [4][5][6][7][8][9] This is critical for the induction and maintenance of AFL, as it prevents the flutter wave from "short-circuiting" across the posterior RA. However, several recent studies have suggested that the CT may not be a consistent barrier to conduction in AFL; some studies showed the presence of a posteromedial functional block in the sinus venosa region, but not on the CT, using intracardiac echocardiography (ICE); [14][15][16] other studies showed double lines of block during AFL, with the first line located along the CT area and the second line located in the sinus venosa region.…”