Left Origin of the Atrial Esophageai Signal as Recorded in the Pacing Site

Abstract

Clear atrial depolarizations from inside the esophagus have always been recorded in electrocardiology, but their precise origin is still under discussion. Though atrial signals are recorded along most of the esophagus, pacing of the atria is possible only in a short tract, probably where the esophagus is in contact with the posterior left atrium wall. In order to ascertain which portion of atria gives rise to the esophageal atrial signal recorded in the atrial pacing segment, we examined 37 patients with normal P waves on the standard ECG by inserting esophageal and endocavitary catheters. The interval between the earliest start of the P wave and the bipolar atrial deflection, was measured both through the esophagus (PA-Eso) and the Hisian region (PA-His) (the latest depolarization of interatrial septum). The former was longer than the latter (P < 0.001) in 36 of 37 patients, showing that the esophagus recorded atrial signal, at the site of effective pacing, originates outside the interatrial septum. As the atrial depolarization recorded through the esophagus is significantly delayed compared with the Hisian region recording, a pure left origin of the esophageal signal can be hypothesized. This is supported by the well-known delayed depolarization, during sinus rhythm, of the left atrium posterior wall compared with the right atrium and interatrial septum. Measuring the interval between the standard ECG P wave and atrial depolarization recorded through esophagus in the site of effective pacing, provides a reliable noninvasive estimate of interatrial time conduction.

Atrial Activation Analysis by Surface P Wave and Multipolar Esophageal Recording After Cardioversion of Persistent Atrial Fibrillation

“…In a first‐level esophageal electrophysiology, obtainable by a simple bipolar lead, the activity of the left atrium can easily be recorded. We obtained the interatrial conduction time as the time interval between the beginning of the surface P wave and the first rapid esophageal atrial depolarization 8 . The results of the present study explain how further electrophysiological information can be achieved by the multipolar esophageal recording which allows the simultaneous recording of two points of the left posterior atrium, superior and inferior, respectively.…”

“…We obtained the interatrial conduction time as the time interval between the beginning of the surface P wave and the first rapid esophageal atrial depolarization. 8 The results of the present study explain how further electrophysiological information can be achieved by the multipolar esophageal recording which allows the simultaneous recording of two points of the left posterior atrium, superior and inferior, respectively. In fact, the particular course of the esophagus permits the mapping of the left atrial posterior wall in the longitudinal direction.…”

“…In clinical practice, when P wave is not clearly evident on the surface ECG, an esophageal lead is commonly used to highlight atrial activity 5‐7 . In a previous study, we demonstrated that the rapid component of the atrial esophageal signal recorded by bipolar technique corresponds to the activation of the posterior wall of the left atrium 8 . Therefore, the interval between the beginning of the P wave on the surface ECG and the fast component of the esophageal atriogram is a good method for evaluating interatrial conduction time.…”

“…Although a universally accepted normal value of interatrial conduction time calculated at esophageal level does not exist, from the data of a study conducted in patients with normal P wave, 8 we considered an IACT value of less than 55 ms a normal cutoff.…”

“…5−7 In a previous study, we demonstrated that the rapid component of the atrial esophageal signal recorded by bipolar technique corresponds to the activation of the posterior wall of the left atrium. 8 Therefore, the interval between the beginning of the P wave on the surface ECG and the fast component of the esophageal atriogram is a good method for evaluating interatrial conduction time. Starting from this landmark, we developed a simple bipolar esophageal technique using a multipolar and sequential recording that, by exploring more than one esophageal tract, appears able to analyze the activation direction of the left posterior atrial wall.…”