Identification of left atrial origin of ectopic tachycardia during right atrial mapping: analysis of double potentials at the posteromedial right atrium

Which side are you on? - Deducing the chamber of origin of atrial tachycardia

Atrial arrhythmias rising from the regions of the atria that are in close proximity to each other may pose a challenge in identifying the chamber to map and ablate in. In this report, we discuss a patient with left atrial tachycardia which initially mimicked right atrial tachycardia. We discuss the origins of the abnormal electrograms in the right atrium and how this provides a general understanding of the mechanism of double potentials.

Mapping strategies in focal atrial tachycardias demonstrating early septal activation: distinguishing left from right

Determining the chamber of origin of focal atrial tachycardias (FATs) arising at or close to the septum might require biatrial mapping. This review focuses on the available tools and methods used to distinguish right atrial from left atrial origin before left atrial access is obtained. These include analysis of P wave morphology, assessing the timing of right atrial septal activation, the sequence of right atrial and/or biatrial activation and analysis of earliest electrogram morphology. The electroanatomical properties of the interatrial septum and coronary sinus that provide the basis for the above mentioned tools have also been briefly described.

Characterization of Focal Atrial Tachycardia Using High-Density Mapping

OBJECTIVES

The goal of this study was to characterize the origin of focal atrial tachycardias (AT).

BACKGROUND

Focal ATs originate from a small area and spread centrifugally; however, activation at the AT origin has not been characterized.

METHODS

Twenty patients with AT having failed prior ablation or occurring after atrial fibrillation ablation were studied. After excluding macro-re-entry, AT was mapped using a 20-pole catheter (five radiating spines; diameter 3.5 cm), performing vector mapping to identify the earliest activity followed by high-density mapping at the AT origin. Localized re-entry was considered if >85% of the tachycardia cycle length (CL) was observed within the mapping field and was confirmed by entrainment.

RESULTS

A total of 27 ATs were mapped to the pulmonary vein ostia (n = 5), and left (n = 16) and right atria (n = 6). A localized focus was evidenced at the site of origin in 19 ATs (70%), whereas in 8 (30%), localized re-entry was evidenced by 95.2 +/- 4.5% of the tachycardia CL recorded within the mapping field and entrainment showed a post-pacing interval <20 ms longer than tachycardia CL (6 of 6 tested). Localized re-entry had a shorter CL (p = 0.009), slowed conduction at its origin (fractionated potential 115 +/- 19 ms vs. 64 +/- 22 ms, representing 49 +/- 10% and 20 +/- 10% of tachycardia CL, respectively; p < 0.0001), and were more often contiguous with regions of electrical silence or conduction abnormalities (88% vs. 32%; p = 0.01). In addition, mapping documented varying degrees of intra-atrial conduction block, preferential conduction (n = 5), and rapid bursts of myocardial activity (n = 1). At 11 +/- 7 months, none have had recurrence of AT.

CONCLUSIONS

High-density multielectrode mapping can be used to perform vector mapping to localize complex AT. It provides novel insight into the mechanisms of focal AT, distinguishing focal AT from localized re-entry.

Electrophysiologic Characteristics of Atrial Tachycardia Originating from the Right Pulmonary Veins or Posterior Right Atrium:. Double Potentials Obtained from the Posterior Wall of the Right Atrium Can Be Useful to Predict Foci of Atrial Tachycardia in the Right Pulmonary Veins or Posterior Right Atrium

INTRODUCTION

The right pulmonary veins (RPVs) and posterior wall of the right atrium (PRA) are anatomically located adjacent to each other. The aim of this study was to demonstrate the electrophysiologic characteristics of atrial tachycardia (AT) originating from the PRA or RPVs.

METHODS AND RESULTS

A total of 26 consecutive patients with AT originating from the RPVs or PRA underwent detailed atrial endocardial mapping and successful radiofrequency catheter ablation. Eight foci were found in the PRA and 18 foci in the RPVs. Analysis of P wave configuration showed that lead V1 was the most helpful in distinguishing the AT foci between these two sites. In all cases, double potential (DP) configurations were recorded from several electrodes of a multielectrode catheter placed in the PRA, and the first DP component (FP) was the earliest potential recorded from the right atrium during the tachycardia. The amplitude of the FP was higher than that of the second DP component (SP) for AT foci originating in the PRA, whereas the reverse occurred for those in the RPV. The activation sequence of the FP was from superior to inferior for the AT foci in the superior RPV, whereas the reverse occurred for the AT foci in the inferior RPV.

CONCLUSION

P wave configuration in lead V1 is helpful in distinguishing AT foci between those originating in the PRA and RPVs. The DPs obtained from the PRA can be useful in predicting whether AT foci originate from the PRA or RPVs.