Magnetic Electroanatomical Mapping for Ablation of Focal Atrial Tachycardias

Abstract

Uniform success for ablation of focal atrial tachycardias has been difficult to achieve using standard catheter mapping and ablation techniques. In addition, our understanding of the complex relationship between atrial anatomy, electrophysiology, and surface ECG P wave morphology remains primitive. The magnetic electroanatomical mapping and display system (CARTO) offers an on-line display of electrical activation and/or signal amplitude related to the anatomical location of the recorded sites in the mapped chamber. A window of electrical interest is established based on signals timed from an electrical reference that usually represents a fixed electrogram recording from the coronary sinus or the atrial appendage. This window of electrical interest is established to include atrial activation prior to the onset of the P wave activity associated with the site of origin of a focal atrial tachycardia. Anatomical and electrical landmarks are defined with limited fluoroscopic imaging support and more detailed global chamber and more focal atrial mapping can be performed with minimal fluoroscopic guidance. A three-dimensional color map representing atrial activation or voltage amplitude at the magnetically defined anatomical sites is displayed with on-line data acquisition. This display can be manipulated to facilitate viewing from any angle. Altering the zoom control, triangle fill threshold, clipping plane, or color range can all enhance the display of a more focal area of interest. We documented the feasibility of using this single mapping catheter technique for localizing and ablating focal atrial tachycardias. In a consecutive series of 8 patients with 9 focal atrial tachycardias, the use of the single catheter CARTO mapping system was associated with ablation success in all but one patient who had a left atrial tachycardia localized to the medial aspect of the orifice of the left atrial appendage. Only low power energy delivery was used in this patient because of the unavailability of temperature monitoring in the early version of the Navistar catheter, the location of the arrhythmia, and the history of arrhythmia control with flecainide. No attempt was made to limit fluoroscopy time in our study population. Nevertheless, despite data acquisition from 120-320 anatomically distinct sites during global and more detailed focal atrial mapping, total fluoroscopy exposure was typically < 30 minutes and was as little as 12 minutes. The detailed display capabilities of the CARTO system appear to offer the potential of enhancing our understanding of atrial anatomy, atrial activation, and their relationship to surface ECG P wave morphology during focal atrial tachycardias.

Maximizing the Effectiveness of Ablation for Arrhythmias in the Congenital Heart Patients

“…Current 3D activation mapping systems play an important role in localizing the source of focal tachycardias and critical isthmuses of reentrant circuits [59][60][61][62][63][64]. The conversion of raw electrical data to "clean" activation maps requires an expert operator to validate the local activation time (LAT) assigned by software algorithm.…”

Electromagnetic Mapping During Complex RF Ablations

“…The published studies involved a limited number of patients, 7 to 120. Focal tachycardias in the right atrium are ablatable with success rate >90% (Kottkamp H et al, 1997;Marchlinski F et al, 1998;Iwai S et al, 2002). The same success rate may be achieved in macroreentrant atrial tachycardia related to post-surgical scar (Iwai S et al, 2002).…”

Atrial Unipolar Potential in Radiofrequency Catheter Ablation of Atrial Tachycardia

“…[11][12][13] These devices are of course very helpful in the rapid determination of the tachycardia origin and reduction of fluoroscopic time. On the other hand, these techniques can sometimes be time-consuming.…”