Role of three-dimensional imaging integration in atrial fibrillation ablation

Figure 1 Three dimensional computed tomography image of a peculiar anatomic variant of the pulmonary veins in a patient with atrial fibrillation and no structural heart disease. A: The postero-anterior view of the left atrium and pulmonary veins; B: The endocardial aspect of the pulmonary vein oses after removal of the anterior wall of the left atrium. The common os of the left and right inferior pulmonary veins is evident both on the epicardial and endocardial (arrows) aspects. The oses of the right and left superior pulmonary veins are adjacent and more anterior, to the common os. LIPV: Left inferior pulmonary vein; LSPV: Left superior pulmonary vein; RIPV: Right inferior pulmonary vein; RSPV: Right superior pulmonary vein.

Figure 2 Postero-anterior view of the electroanatomic activation mapping of the left atrium and pulmonary veins. These have been reconstructed as five separate chambers using the Carto system and acquiring a few sites while the mapping catheter is manipulated in these anatomic structures. Colors indicate the activation sequence from the earliest in red (antero-medial part of the left atrium) to the latest in dark blue (postero-lateral part of the left atrium and distal part of the pulmonary veins). LA: Left atrium; LIPV: Left inferior pulmonary vein; LSPV: Left superior pulmonary vein; RIPV: Right inferior pulmonary vein; RSPV: Right superior pulmonary vein.

Figure 3 Postero-anterior view of the electroanatomic map shown in Figure 2 and of the three-dimensional rendering of the computed tomography scan, both in a postero-anterior view. A couple of points (small red flags on the electroanatomic mapping and computed tomography) have been identified on the left atrial roof. These two landmarks will be used to initially guide the superimposition of the two surfaces. CT: Computed tomography.

Figure 4 The two surfaces have been superimposed based on the guide provided by the two landmarks. The match of the two surfaces has been further improved with the so-called “surface registration” option, obtaining optimal integration. The accuracy of this process is then checked by verifying the distance between each electroanatomic point and the corresponding site on the computed tomography surface. In this case, all sites in the electroanatomic maps are marked by a green dot, which identifies the distance between the two surfaces as < 5 mm.

Figure 5 After completing the imaging integration process, pulmonary vein ablation is initiated. The screen of the electroanatomic system shows simultaneously the epicardial (upper) and endocardial (down) aspects of the high resolution computed tomography image of the common os of the left pulmonary veins present in this patient. The green circular icon identifies the multipolar circular mapping catheter, positioned inside the common os to verify its electrical disconnection. The icon of the ablation catheter (white arrows) is also visible, so that this catheter can be manipulated to navigate the three-dimensional computed tomography image with minimal or no use of fluoroscopy. Each red dot marks the site where radiofrequency energy has been applied along the veno-atrial junction of the left pulmonary veins to achieve their electrical disconnection. LIPV: Left inferior pulmonary vein; LSPV: Left superior pulmonary vein; LAA: Left atrial appendage.