Computed tomography model-based treatment of atrial fibrillation and atrial macro-re-entrant tachycardia

Abstract

Aims: Accurate orientation within true three-dimensional (3D) anatomies is essential for the successful radiofrequency (RF) catheter ablation of atrial fibrillation (AF) and atrial macro-re-entrant tachycardia (MRT). In this prospective study, ablation of AF and MRT was performed exclusively using a pre-acquired and integrated computed tomography (CT) image for anatomical 3D orientation without electro-anatomic reconstruction of the left atrium (LA).

Methods and results: Fifty-four consecutive patients suffering from AF (n = 36) and/or MRT (n = 18) underwent RF catheter ablation. A 3D CT image was registered into the NavX-Ensite system without reconstruction of the atrial chamber anatomy. The quality of CT alignment was assessed and validated according to fluoroscopy information, electrogram characteristics, and tactile feedback at 31 pre-defined LA control points. The ablation of AF as well as mapping and ablation of MRT was performed within the 3D CT anatomy. In all patients, mapping and ablation could be performed without the reconstruction of the respective atrial chamber anatomy. The overall CT alignment was highly accurate with true surface contact in 90% (84%; 100%) of the control points. Complete isolation of all pulmonary vein (PV) funnels was achieved in 35 of 36 patients (97%) with AF. In patients with persistent AF (n = 11), additional isolation of the posterior LA (box lesion) and the placement of a mitral isthmus line were performed. The MRT mechanisms were as follows: around a PV ostium (n = 6), perimitral (n = 4), through LA roof (n = 5), septal (n = 2), and around left atrial appendage (n = 1). After a follow-up of 122 +/- 33 days, 22/25 (88%) patients with paroxysmal AF, 8/11 (73%) with persistent AF, and 16/18 (89%) with MRT remained free from arrhythmia recurrences.

Conclusion: For patients with AF and MRT, our study shows the feasibility of successful placement of complex linear ablation line concepts guided by an integrated 3D image anatomy alone rather than catheter-based virtual chamber surface reconstructions.

Keywords: Ablation; Atrial fibrillation; Model-guided therapy; Three dimensional image.

Figures

Figure 1

Main step for registering the three-dimensional computed tomography image of the left atrium into the real-time mapping system. Registration is based on reconstruction of the four pulmonary vein anatomies. (A) Pulmonary vein reconstruction was achieved through automatic anatomic point acquisition through all 10 poles of a multipolar circular mapping catheter while slowly withdrawing the catheter out of each pulmonary vein (in the picture, the left upper pulmonary vein). (B) Sync view of the four reconstructed pulmonary vein anatomies (blue, left upper pulmonary vein; yellow, left lower pulmonary vein; purple, right upper pulmonary vein; brown, right lower pulmonary vein) and the imported three-dimensional computed tomography image, before registration. (C) Alignment between the NavX reconstructed pulmonary vein anatomies and the pulmonary veins of the three-dimensional computed tomography image. After that main registration step, further fine adjustment was achieved through three pre-defined landmark points (left atrium roof, basal left atrium, and left atrium isthmus) visited with the ablation catheter.

Figure 2

Control points that had to be visited with the catheter tip to assess the alignment accuracy by two independent electrophysiologists. Control point location and tissue contact were reached and assessed according to fluoroscopy information, electrogram characteristics, and tactile feedback. For each of the control points, the position of the catheter tip in relation to the registered computed tomography surface was evaluated in a nominal fashion (1–4, septal/inferior/posterior/superior mitral annulus; 5, left atrium isthmus; 6, tissue bridge between left atrium appendage and left upper pulmonary vein; 7–22, anterior/inferior/posterior/superior wall of each pulmonary vein; 23–25, left-sided, middle, and right-sided left atrium roof; 26–28, left-sided, middle, and right-sided basal left atrium; 29–31, annular, middle, and posterior part of the left atrium septum).

Figure 3

Following computed tomography registration and before the beginning of the ablation procedure, the oesophagus was intubated with an additional catheter, and the oesophageal anatomy was reconstructed through automatic point acquisition while slowly withdrawing the catheter out of the oesophagus. Contact and vicinity between the oesophageal anatomy reconstruction and the left atrial computed tomography anatomy was visualized. Example of a so-called B-position, where the oesophagus is positioned towards the left-sided pulmonary veins with contact at the posterior wall of the antrum of the left lower pulmonary vein (dark brown, left upper pulmonary vein; purple, left lower pulmonary vein; blue, right upper pulmonary vein; yellow, right lower pulmonary vein; light brown, oesophagus).

Figure 4

Left atrial ablation procedures in patients presenting with paroxysmal and persistent atrial fibrillation. Ablation points were marked as ‘three-dimensional Lesion on EnGuide’ (red-coloured lesion points), which documents the true three-dimensional localization of the catheter tip (no projection on computed tomography surface and no ‘Lesion at Mouse’). The true position of the catheter tip on the computed tomography surface can be appreciated for all ablation target areas, underlining the registration accuracy. Pink-coloured lesion points represent ablation in areas with oesophageal vicinity (energy reduction to 30 W and shorter ablation duration). (A) Example of a patient with paroxysmal atrial fibrillation. Circumferential left atrial lesions were deployed around the funnels of the left- and right-sided pulmonary veins. As an anatomical variation, this patient presented with a common funnel of the left-sided pulmonary veins. (B) Example of a patient with persistent atrial fibrillation. After circumferential left atrial ablation, additional linear ablation lines were placed in the left atrium for further substrate modification (left atrium roof, left atrium isthmus, and posterior basal left atrium). The resulting ‘box-lesion’ at the posterior left atrium was completely isolated using voltage and pace mapping criteria.

Figure 5

Example of a patient with a left atrial macro-re-entrant tachycardia. The left panel shows the pure three-dimensional computed tomography anatomy after registration. The NavX reconstructed pulmonary veins are hidden. The distal part of each pulmonary vein is cut off for image clarity. Locations within the computed tomography anatomy were visited with the ablation catheter. In stable catheter positions (small yellow points), entrainment mapping was performed. The right panel illustrates the colour-coded entrainment information in a three-dimensional fashion. Red colours representing areas with a short return cycle (close to the re-entrant circuit) and purple colours representing areas with a long return cycle (far away from the re-entrant circuit). ‘Isochronal lines’ connect locations with a similar length of the return cycle. The map clearly shows a macro-re-entrant circuit around the right lower pulmonary vein. Circumferential ablation around the antrum of the right-sided pulmonary veins terminated the tachycardia.