Left Atrial Anterior Wall Scar-Related Atrial Tachycardia in Patients after Catheter Ablation or Cardiac Surgery: Electrophysiological Characteristics and Ablation Strategy

Figure 1. Simplified schemas of six subtypes of the left atrial anterior wall (LAAW) atrial tachycardia (AT) reentrant circuits. (A), Type 1.1: Single-looped macro-reentrant AT with one single LAAW gap as the critical area. The propagation of AT ran across the LAAW gap and around the mitral valve annulus (MVA). (B), Type 1.2: The propagation course was similar to Type 1.1, except that there were multiple LAAW gaps. The propagation of AT ran around the MVA and went across all the LAAW gaps. (C), Type 1.3: Dual-looped AT with LAAW conduction gap(s) as the critical area. The wavefront simultaneously propagated around a pre-existing LA roof scar and ran around the LAAW scar and MVA. (D), Type 2.1: Single-looped bi-atrial reentrant ATs whose circuit used both LA and RA. The wavefront activated RA at the superior septum consistent with RA insertion of BB, running down the septum and jumped to LA through fossa ovalis or coronary sinus ostium. Then the wavefront ran around the MVA counterclockwise to LAAW, returning to the LA insertion of BB to complete the circuit. (E), Type 2.2: LAAW epicardial macro-reentrant AT featured by an epicardial connection crossing the pre-existing linear lesion. The…

Figure 2. The high-density mapping of a Type 1.1 AT. (A) Activation map of a Type 1.1 AT from the anteroposterior view (left) and the left-anterior oblique view (right). The LA high-density mapping identified one LAAW block line stretching from the right superior pulmonary vein (RSPV) to the MVA, with a conduction gap near the RSPV end. The wavefront of AT ran along the LAAW line upwards in LA septum to jump across the LAAW gap, then ran toward MI and around the MVA clockwise, and returned to LA septum. The arrowed red lines indicated the AT circuit; the dashed red line indicated the AT circuit behind the atrial structure; the jagged red line indicated the wavefront passing the slow conduction area; the double-dashed blue line indicated the LAAW block of line. (B) Local map potentials of the LAAW gap during AT (left) and at the moment of AT termination (bottom). The red dots indicated the ablation points; the green dot indicated the termination site; the arrowed red and yellow lines indicated the local potentials during AT and at the moment of AT termination, respectively.

Figure 3. The high-density mapping of a Type 1.2 AT. (A) Activation map of a Type 1.2 AT from the anteroposterior view (left) and the left-anterior oblique view (right). The LA high-density mapping identified one LAAW block line from the RSPV to the MVA, with three conduction gaps at the MVA end, near the RSPV end, and in the middle of the LAAW line. The wavefront of AT ran down the LA septum, go along the MVA counterclockwise, and reached the LAAW after passing the MI, then the wavefront jumped across the LAAW conduction gaps almost simultaneously and returned to the LA septum. The red lines with arrows indicated the circuit of AT; the dashed red line indicated the circuit of AT behind the atrial structure; the jagged red lines indicated the wavefront passing the slow conduction areas; the double-dashed blue line indicated the LAAW block of line. (B) Local map potentials of the LAAW gap during AT (left) and at the moment of AT termination (bottom). The red dots indicated the ablation points; the green dot indicated the termination site; the arrowed red and yellow lines indicated the local potentials during AT and at the moment of AT termination, respectively.

Figure 4. The high-density mapping of a Type 1.3 AT. (A) Activation map of a Type 1.3 AT from the anteroposterior view with additional cranial tilt (left) and the left-anterior oblique view with additional cranial tilt (right). The LA high-density mapping identified two block lines, including one LAAW block line from the RSPV to the MVA and one roof block line between the RSPV and the left superior pulmonary vein (LSPV). Two conduction gaps were identified, including one at the RSPV end of the LA roof line and the other at the RSPV end of the LAAW line. This was a dual-looped AT, and the activation propagated around the LA roof scar and the MVA simultaneously. The wavefront ran in LAAW from the right pulmonary vein antrum toward the LA free wall, turned around the MI and activated the LA posterior wall, and then divided into two branches: (1) the wavefront ran up and propagated along the LA roof line, went across the roof line conduction gap and returned to the LAAW; (2) the wavefront ran around the MVA, propagated upward in the LA septum, went across the LAAW conduction gap and returned to the LAAW. The red lines with arrows indicated the circuit of AT; the dashed red line indicated the…

Figure 5. The high-density mapping of a Type 2.1 AT. (A) Activation map of a Type 2.1 AT from the anteroposterior view of LA (left) and the left-anterior oblique view of LA and RA (right). The high-density mapping identified one LAAW block line from the RSPV to the MVA, and the wavefront activated RA at the superior septum consistent with RA insertion of BB, ran down the septum and jumped to LA via the coronary sinus ostium. Then the wavefront ran around the MVA counterclockwise to LAAW and returned to RA via the insertion of BB near LA roof. The red lines with arrows indicated the circuit of AT; the dashed red line indicated the circuit of AT behind the atrial structure; the dotted red lines indicated the inter-atrial bypasses; the arrowed white line indicated passive activation; the double-dashed blue line indicated the LAAW block of line. (B) Local map potentials of the LAAW gap during AT (left) and at the moment of AT cycle length change (bottom). The red dots indicated the ablation points; the green dot indicated the ablation site of cycle length change; the arrowed red and yellow lines indicated the local potentials during AT and at the moment of AT cycle length change (from 221 ms…

Figure 6. The high-density mapping of a Type 2.2 AT. (A) Activation map of a Type 2.2 AT from the anteroposterior view (left) and the left-anterior oblique view (right). The high-density mapping identified one LAAW block line stretching from LA septum extending to LA roof. The wavefront ran down the LA posterior wall, turned around the MI and activated LAAW, then jumped across the LAAW block line via the epicardial bypass and activate the other side in an areal pattern. Then the wavefront went upward around the LA roof and returned to the LA posterior wall. The red lines with arrows indicated the circuit of AT; the dashed red line indicated the epicardial bypass of the AT circuit; the dotted red line indicated the epicardial bypass; the double-dashed blue line indicated the LAAW block of line. (B) Local map potentials of the LAAW gap during AT (left) and at the moment of AT termination (bottom). The red dots indicated the ablation points; the green dot indicated the termination site; the arrowed red and yellow lines indicated the local potentials during AT and at the moment of AT termination, respectively.

Figure 7. The high-density mapping of a Type 3 AT. (A) Activation map of a Type 3 AT from the anteroposterior view (left) and the left-anterior oblique view (right). The high-density mapping identified one minor LAAW block line near the MVA and one LAAW scar. The wavefront ran around the minor LAAW scar and propagated in a centrifugal pattern to activate other part of the LA. The red line with arrows indicated the circuit of AT; the jagged red line indicated the wavefront passing the slow conduction area; the white lines with arrows indicated passive activation; the white dashed lines indicated passive activation behind the atrial structure; the double-dashed blue line indicated a minor LAAW block of line. (B) Local map potentials of the LAAW gap during AT (left) and at the moment of AT termination (bottom). The red dots indicated the ablation points; the green dot indicated the termination site; the arrowed red and yellow lines indicated the local potentials during AT and at the moment of AT termination, respectively.

Figure 8. Kaplan-Meier survival curve showing cumulative freedom from atrial tachy-arrhythmia after ablation. ATa, atrial tachy-arrhythmia; CI, confidential interval.