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Characterization of Focal Atrial Tachycardia Using High-Density Mapping

Prashanthan Sanders, MBBS, PhD^_*,,_*, Mélèze Hocini, MD^_*,, Pierre Jaïs, MD^_*,, Li-Fern Hsu, MBBS^_*,, Yoshihide Takahashi, MD^_*,, Martin Rotter, MD^_*,, Christophe Scavée, MD^_*,, Jean-Luc Pasquié, MD, PhD^_*,, Fréderic Sacher, MD^_*,, Thomas Rostock, MD^_*,, Chrishan J. Nalliah, BSc^_*,, Jacques Clémenty, MD^_*, and Michel Haïssaguerre, MD^_*,

^_* Hôpital Cardiologique du Haut-Lévêque, Bordeaux, France
Université Victor Segalen Bordeaux-II, Bordeaux, France.

View larger version (70K): [in a new window]   Figure 1 (A) Shows a picture and a fluoroscopic image of the high-density mapping catheter. Below each figure is a schematic representation indicating the orientation of the catheter spines. Note the marker band on spine-A is between electrodes 1 to 2, and on spine-B between electrodes 2 to 3. (B) Demonstrates vector mapping to identify the earliest site of activation. Shown is the catheter in four distinct locations within the left atrium (LA). Mapping is commenced along the inferior LA where the earliest activation is 54 ms ahead of the coronary sinus (CS). The catheter is moved in the direction of the spine demonstrating the earliest activation (spine-D). In the mid-posterior LA, activation precedes the CS by 62 ms. Again the catheter is moved in the earliest direction (spine-D) to a more cranial location on the LA roof. At this site, activation precedes the CS by 75 ms. At this site, spine-B, which is slightly anterior, is the earliest. Moving the catheter in the direction of spine-B to the anterior-superior LA demonstrates the site with the earliest endocardial activation (90 ms ahead of the CS, which was 40 ms ahead of the P-wave).

View larger version (31K): [in a new window]   Figure 2 Schematic representation of the location of atrial tachycardias in this cohort. Each dot represents a focal tachycardia, and localized re-entry is represented by arrows (blue for those without and black for those with a history of atrial fibrillation). CS = coronary sinus; IVC = inferior vena cava; LAA = left atrial appendage; MV = mitral valve; RAA = right atrial appendage; SVC = superior vena cava; TV = tricuspid valve.

View larger version (27K): [in a new window]   Figure 3 Anterior left atrial tachycardia focus at the center of the mapping catheter. Demonstrated are the electrograms and a schematic representation of activation. The catheter was positioned directly on the site of the tachycardia focus and resulted in a proximal-to-distal activation on four or five spines of the catheter. In this case, spine-D demonstrates the earliest activity and the smallest activation gradient of all spines. Ablation at this site terminated tachycardia. Note the much smaller relative activation time difference between electrodes on account of the localized mapping, compared to conventional activation mapping. CS = coronary sinus.

View larger version (77K): [in a new window]   Figure 4 Localized re-entry as a mechanism of atrial tachycardia centrifugally activating the remaining atria. This example is in near proximity to the previous right inferior pulmonary vein (PV) ablation. (A) Represents activation mapping demonstrating centrifugal activation of the left atrium from an area immediately anterior to the still-isolated right-inferior PV. (B) Demonstrates the positioning of the high-density catheter in this region and the resultant activation sequence is shown in (C). Re-entry was confirmed by entrainment, and ablation successfully terminated tachycardia (brown tags, A). Note that spine-A and -B are within the isolated PV. CSD = distal coronary sinus; CSP = proximal coronary sinus.

View larger version (45K): [in a new window]   Figure 5 Localized re-entry occurring at a site not in proximity to previous ablation. (A) Demonstrates tachycardia arising from the anterior-superior left atrial (LA) wall. Electrograms from only spine-C and -D have been presented to demonstrate the cascade of activation (spine-C is organized from distal-to-proximal and spine-D from proximal-to-distal). Note each spine in this case was configured to provide three bipoles. Also shown is a schematic representation of the activation cascade. Entrainment confirmed a re-entrant mechanism, and ablation terminated tachycardia. (B and C) Demonstrate activation and entrainment of tachycardia in a different patient. Tachycardia was localized on the anterior-septal LA wall. Entrainment demonstrates a post-pacing interval 12 ms longer than the tachycardia cycle length (CL). In this patient, entrainment could be performed from three sites in the mapping field and were as above. However, entrainment performed in the surrounding atria demonstrated post-pacing intervals 40 ms longer than tachycardia CL. CS = coronary sinus.

View larger version (64K): [in a new window]   Figure 6 Localized re-entry in a patient without a history of atrial fibrillation. (A) Presents the electroanatomic voltage map (lateral right atrial en face) created during this patient’s previous mapping procedure (before ablation) together with the electrocardiographic features of the tachycardia. Note the low-amplitude P-wave (*). (B) shows the catheter position immediately superior to the region of electrical silence with (C) showing the resulting activation at the site of origin. The electrograms in this patient have not been arranged, but activity is observed throughout the tachycardia cycle length and is demonstrated visually in the schematic (D). In this patient, the atria could not be captured to perform entrainment from this site. AP = anterior-posterior; RL = right lateral.

View larger version (39K): [in a new window]   Figure 7 (A) Shows the electrocardiogram of an atrial tachycardia with apparent start-stop episodes. (B, top panel) Shows the intracardiac electrograms with the high-density mapping catheter. In this region of atrial electrical silence, two spines record electrical activity. During the pause on the electrocardiogram, activity persists at the origin of the tachycardia on spine-E while there is intra-atrial conduction block that gives rise to the misleading appearance of tachycardia cessation. However, note that the P-wave morphology after the pause is not typical of sinus rhythm. (B, bottom panel) This is also from the same patient and was observed earlier in the mapping process. This recording was observed in the lateral right atrium, again in the midst of an area of electrical silence; spine-D alone demonstrates high-frequency activity. Although surprising that the atria could demonstrate activity at such a rate (mean cycle length 83 ms), this was indeed a sequestrated island of activity that was isolated from the remaining atria. Ablation eliminated the local activity but did not change tachycardia. CS = coronary sinus.

View larger version (61K): [in a new window]   Figure 8 High-density mapping of a tachycardia focus along the crista terminalis demonstrating the phenomenon of preferential conduction from origin-to-exit or breakout point to the remaining atria. This occurred in a 46-year-old man who presented with atrial tachycardia after having undergone pulmonary vein isolation, left atrial linear ablation, and cavotricuspid isthmus ablation for permanent atrial fibrillation (the crista terminalis had not previously been targeted by ablation). There is reversal of activation of potential on spine-C with the ectopic beat, which then spreads to the adjacent spine-B. At B5–6 continuous activity is observed followed by activation of the remaining atria. A second concealed beat is seen to arise from the origin (C10–11) and traverses to the exit point at B5–6. At this site conduction block is observed to the remaining atria. With longer coupling intervals, such ectopy was observed to excite the whole atria. CS = coronary sinus.