Atrial Activation Mapping in Sinus Rhythm in the Clinical Electrophysiology Laboratory:

Abstract

During stable sinus rhythm, RA activation can start in different areas or simultaneously over large areas resulting in different activation patterns, both in the RA and the LA. LA activation is predominantly descending, but in Bachmann's bundle block it becomes ascending, and double potentials suggest a location of block in the LA roof.

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

“…Firstly, it offers a simple, non-invasive method of determining interatrial conduction, which is likely to reflect the propensity for atrial arrhythmia 14,17,18 in large patient cohorts. It is also likely to offer a means of optimizing the choice of septal pacing site in order to resynchronize the atria when pacemaker therapy is chosen for treatment of patients with severe paroxysmal atrial fibrillation.…”

“…14,16,27 It was noted that the presence of a 8 biphasic signal in Lead Y (Type 3) was always accompanied by a biphasic Lead Z (as illustrated in Figures 1 and 2), hence the activation direction in Type 3 morphology was not only characterized by the superior-to-inferior-to-superior route, but also posterior-to-anteriorto-posterior propagation, indicating not only a Bachmann's bundle block, but also a block or delayed conduction in the posterior route. In other words, it was hypothesized that Type 1 morphology corresponds to conduction via the fossa ovalis with or without simultaneous conduction via other routes; that Type 2 morphology corresponded to Bachmann's bundle conduction with or without simultaneous conduction via the coronary sinus, and finally, that Type 3 morphology was the result of conduction via the coronary sinus without any other noticeable interatrial conduction.…”

“…11,12 This is primarily thought to be mediated by a delay in the conduction over Bachmann's bundle. 13 Advanced interatrial block, which has been shown to be caused by complete blockage of Bachmann's bundle, 14 is seen as a prolonged, biphasic P wave in the inferior leads. 15,16 Interatrial block of any degree has been shown to be associated with a high propensity for atrial arrhythmia, including atrial fibrillation.…”

“…15,16 Interatrial block of any degree has been shown to be associated with a high propensity for atrial arrhythmia, including atrial fibrillation. 14,17,18 However, the risk of developing atrial arrhythmia is substantially higher in cases of advanced interatrial block. 18 With the exception of these rather crude indices of impaired interatrial conduction, it has not until now been possible to extract any further information regarding interatrial conduction from the standard 12-lead ECG.…”

Abnormal atrial activation is common in patients with arrhythmogenic right ventricular cardiomyopathy

“…In particular, 38% of ARVC patients had atypical P waves not meeting predefined morphology criteria with activation vector directed posteriorly in the sagittal plane (Atypical or Type 4) that appeared as positive P waves in lead Z. One ARVC patient had a P wave that met criteria for advanced interatrial block with retrograde activation of the left atrium, 18,19 i.e. biphasic P wave morphology in inferior leads and P wave duration >120 ms (Type 3).…”