Human Study of Biatrial Electrical Coupling

Abstract

Background-The relative contribution of the atrial septum and interatrial connections to biatrial activation is a fundamental concept of human cardiac electrophysiology that has yet to be fully characterized. The purpose of the present study was to determine how both atria are coupled electrically. Methods and Results-Twenty patients (16 men; mean age 54Ϯ11years) with a history of symptomatic atrial fibrillation (AF) underwent simultaneous biatrial noncontact mapping before catheter ablation of AF. The multiple electrode array catheters were positioned, respectively, in the left atrium (LA; transseptally) and the right atrium (RA). In all but 2 patients, isopotential maps revealed that endocardial septal activations of the RA and LA were separate, independent, and asynchronous of each other. Interatrial conduction was related to the site of initial atrial depolarization, revealing conduction over Bachmann's bundle in all patients during sinus rhythm, high RA pacing, and pacing from the LA appendage. Pacing from the coronary sinus was associated with conduction over the interatrial connection at the level of the coronary sinus in all patients, and conduction over Bachmann's bundle also occurred in 5 (26%) of 19 patients. Interatrial conduction over the fossa ovalis occurred in only 2 (2%) of the 116 segments analyzed. Conclusions-Electrical coupling of the RA and LA in humans is predominantly provided by muscular connections at the level of Bachmann's bundle and the coronary sinus. The true septum (the fossa ovalis and its limbus) of the RA and LA is asynchronous and discordant, usually without contralateral conduction during sinus rhythm or atrial pacing.

Mechanism Underlying Initiation of Paroxysmal Atrial Flutter/Atrial Fibrillation by Ectopic Foci

“…The LA and RA are connected through 3 interatrial connections: the Bachmann's bundle, fossa ovalis, and coronary sinus as observed with simultaneous biatrial noncontact mapping in humans. 13 By assigning different diffusion coefficients, as suggested previously, 8,12 we obtained heterogeneous conduction regions in the atria ( Figure IIB in the online-only Data Supplement). Specifically, the conduction velocities were 65 cm/s in the bulk tissue, 120 cm/s in the fast bundles, and 36 cm/s in the slow-conduction region.…”

Characteristics of Cavotricuspid Isthmus–Dependent Atrial Flutter After Left Atrial Ablation of Atrial Fibrillation

“…This observation confirms the preeminence of Bachmann's bundle in providing synchronous atrial activation. 14 …”

Interatrial conduction can be accurately determined using standard 12-lead electrocardiography: Validation of P-wave morphology using electroanatomic mapping in man

“…[2][3][4] Nevertheless, based on the data available, it seems reasonable to conclude that Bachmann's bundle is the most common interatrial conductive route, although other routes, located posteriorly 6,7 and inferiorly, [8][9][10] also participate in interatrial conduction in most patients.…”

“…However, knowledge about normal interatrial conduction during sinus rhythm in the intact human heart is based on a few reports on patients with clinical arrhythmia, using various invasive techniques. [1][2][3][4][5] The results are to a certain degree conflicting, with the proportion of patients showing activation of the left atrium via…”